| Gabba Island | Queensland | 4.16 km² | 0 | 26 m |
| Gabo Island | Victoria | — | — | 36 m |
| Gaferut | Yap State | 0.13 km² | 0 | — |
| Gag Island | Raja Ampat | 61.9 km² | 450 | 132 m |
| Gagaseng Natuk Island | Fakfak | 0.00 km² | — | — |
| Gagaseng Nenem Island | Fakfak | 0.01 km² | — | — |
| Gagil-Tamil | Yap State | 28.8 km² | 1,670 | — |
| Gaibirra Island | Queensland | — | — | 63 m |
| Gaike Island | Aru Islands Regency | 0.00 km² | — | — |
| Gainaulai Islet | Queensland | — | — | 19 m |
| Gairgoraman Jina Island | Aru Islands Regency | 0.20 km² | — | — |
| Gairgoraman Sisiay Island | Aru Islands Regency | 0.02 km² | — | — |
| Galahi Island | Milne Bay Province | 0.92 km² | — | 80 m |
| Galakauguria Island | Aru Islands Regency | 0.04 km² | — | — |
| Galampop Island | Raja Ampat | 0.05 km² | — | — |
| Galang Island | Aru Islands Regency | 0.07 km² | — | — |
| Galyu Ganan Island | Raja Ampat | 0.01 km² | — | — |
| Galyu Island | Raja Ampat | 0.05 km² | — | — |
| Galyu Island | Raja Ampat | 0.05 km² | — | — |
| Galyu Pale Island | Raja Ampat | 0.18 km² | — | 25 m |
| Galyu Palolon Island | Raja Ampat | 0.01 km² | — | — |
| Galyulo Island | Raja Ampat | 0.01 km² | — | — |
| Gam Island | Raja Ampat | 194.1 km² | — | 155 m |
| Gam Island | Raja Ampat | — | — | 4 m |
| Gam Le Island | Raja Ampat | 0.00 km² | — | — |
| Gam Lol Island | Raja Ampat | 0.01 km² | — | — |
| Gam Mirinle Island | Raja Ampat | 0.01 km² | — | — |
| Gamfi Batan Lapo Island | Raja Ampat | 0.01 km² | — | — |
| Gamfi Kapatcol Lutoluya Island | Raja Ampat | 0.00 km² | — | — |
| Gamfi Kapatcol Pale Laleltoleya Island | Raja Ampat | 0.01 km² | — | — |
| Gamfi Kapatcol Tofat Island | Raja Ampat | 0.00 km² | — | — |
| Gamfi Kapatcol Tol Island | Raja Ampat | 0.00 km² | — | — |
| Gamfi Kapatcol Toleya Island | Raja Ampat | 0.00 km² | — | — |
| Gamfi Kapatcol Toyoklolo Island | Raja Ampat | 0.00 km² | — | — |
| Gamfi Nikapatcol Paletolennataya Island | Raja Ampat | 0.00 km² | — | — |
| Gamfi Yefto Lalellollo Island | Raja Ampat | 0.00 km² | — | — |
| Gamfi Yefto Yasancau Island | Raja Ampat | 0.00 km² | — | — |
| Gamgom Nikaleo Island | Raja Ampat | 0.00 km² | — | — |
| Gampunut Island | Raja Ampat | 0.04 km² | — | 13 m |
| Gamta Kale Keto Island | Raja Ampat | 0.02 km² | — | — |
| Ganan Les Island | Raja Ampat | 0.01 km² | — | — |
| Ganan Lool Island | Raja Ampat | 0.01 km² | — | — |
| Gananggarngur Island | Northern Territory | — | — | 18 m |
| Gandagara Island | New South Wales | — | — | 8 m |
| Gangal Island | Aru Islands Regency | 0.64 km² | — | — |
| Gangonlol Yef Pale Island | Raja Ampat | 0.02 km² | — | — |
| Ganumbali Island | Northern Territory | — | — | 16 m |
| Garar Island | Aru Islands Regency | 0.01 km² | — | — |
| Garden | Queensland | — | — | 17 m |
| Garden Island | South Australia | — | — | 8 m |
| Garden Island | Queensland | — | — | 30 m |
| Garden Island | Tasmania | — | — | 3 m |
| Garden Island | New South Wales | — | — | 4 m |
| Garden Island | New South Wales | — | — | 1 m |
| Garden Island | Queensland | — | — | 165 m |
| Garden Island | South Australia | — | — | 23 m |
| Garden Island | South Australia | — | — | 4 m |
| Garden Island | Tasmania | — | — | 44 m |
| Garden Island | New South Wales | — | — | 8 m |
| Gariasababil Island | Aru Islands Regency | 0.02 km² | — | — |
| Garja Island | Aru Islands Regency | 0.66 km² | — | — |
| Garogos Island | Eastern Seram | 0.09 km² | — | 195 m |
| Garove | West New Britain Province | 52 km² | 3,617 | — |
| Garua Island | West New Britain Province | 8.50 km² | — | — |
| Gasal Leatsa Island | Raja Ampat | 0.00 km² | — | — |
| Gasal Lelu Island | Raja Ampat | 0.00 km² | — | — |
| Gasal Letol Island | Raja Ampat | 0.00 km² | — | — |
| Gasal Lol Island | Raja Ampat | 0.03 km² | — | — |
| Gasirakargwai Island | Aru Islands Regency | 0.00 km² | — | — |
| Gathering Island | Tasmania | — | — | 7 m |
| Gau Island | Lomaiviti | 136.1 km² | 8,000 | 738 m |
| Gaua | Torba | 328.2 km² | 2,491 | 455 m |
| Gayamoar Island | Teluk Bintuni | 75.0 km² | — | — |
| Gayang Island | Raja Ampat | 0.46 km² | — | 9 m |
| Gelayef Island | Raja Ampat | 0.01 km² | — | — |
| Gelem Island | Raja Ampat | 0.58 km² | — | 9 m |
| Gells Island | New South Wales | — | — | 49 m |
| Gells Island | New South Wales | — | — | 50 m |
| Gelo Island | Sorong | 0.15 km² | — | 14 m |
| Gem Rock | Tasmania | — | — | 15 m |
| Gemfin Island | Aru Islands Regency | 0.00 km² | — | — |
| Gemut Island | Raja Ampat | 1.17 km² | — | 60 m |
| George Island | Queensland | — | — | 34 m |
| George Rocks | Tasmania | 7 km² | 0 | 6 m |
| Gereeba Island | New South Wales | — | — | 7 m |
| Geri Island | Fakfak | 0.00 km² | — | — |
| Germa Island | Sorong | 0.24 km² | — | — |
| Germa Selatan Island | Sorong | 0.04 km² | — | — |
| Germa Utara Island | Sorong | 0.06 km² | — | — |
| Germein Island | South Australia | — | — | 1 m |
| Geser Island | Eastern Seram | 0.49 km² | — | 3 m |
| Gesila Island | Milne Bay Province | 0.17 km² | — | 61 m |
| Getullai Island | Queensland | — | — | 9 m |
| Gewe Ganan Island | Raja Ampat | 0.00 km² | — | — |
| Gewe Palay Island | Raja Ampat | 0.00 km² | — | — |
| Gigi Island | Fakfak | 0.00 km² | — | — |
| Gigisiasi Island | Fakfak | 0.01 km² | — | — |
| Gilbert Island | Northern Territory | — | — | 7 m |
| Gilia Island | Milne Bay Province | 0.36 km² | — | — |
| Ginuninusa Island | Fakfak | 0.01 km² | — | — |
| Ginyommat Pale Island | Raja Ampat | 0.06 km² | — | — |
| Girlies Island | Southland Region | — | — | 77 m |
| Girt Island | Queensland | — | — | 4 m |
| Girung Island | Queensland | — | — | 1 m |
| Gitunum Island | Raja Ampat | 0.44 km² | — | 31 m |
| Glasgow Island | Marlborough District | — | — | 331 m |
| Glebe Island | New South Wales | — | — | 14 m |
| Gloucester Island | Queensland | — | — | 502 m |
| Goaribari Island | Gulf Province | 40 km² | 100 | — |
| Goat | New South Wales | — | — | 87 m |
| Goat Island | South Australia | — | — | 39 m |
| Goat Island | South Australia | — | — | 4 m |
| Goat Island | South Australia | — | — | 3 m |
| Goat Island | Queensland | — | — | 18 m |
| Goat Island | Queensland | — | — | 1 m |
| Goat Island | Queensland | — | — | 135 m |
| Goat Island | New South Wales | — | — | 2 m |
| Goat Island | New South Wales | — | — | 14 m |
| Goat Island | New South Wales | — | — | 3 m |
| Goat Island | New South Wales | — | — | 4 m |
| Goat Island | South Australia | — | — | 20 m |
| Goat Island | New South Wales | — | — | 3 m |
| Goat Island | New South Wales | — | — | 1 m |
| Goat Island | Northern Territory | — | — | 8 m |
| Goat Island | Queensland | — | — | 8 m |
| Goat Island | South Australia | — | — | 1 m |
| Goat Island | South Australia | — | — | 1 m |
| Goat Island | Victoria | — | — | 91 m |
| Goat Island | Victoria | — | — | 5 m |
| Goat Island | Victoria | — | — | 3 m |
| Goat Island | New South Wales | — | — | 1 m |
| Goat Melmel | New South Wales | — | — | 1 m |
| Goats Island | New South Wales | — | — | 3 m |
| Godil Island | Aru Islands Regency | 0.03 km² | — | — |
| Gofa Island | Eastern Seram | 0.06 km² | — | 40 m |
| Gofane Island | Aru Islands Regency | 0.49 km² | — | — |
| Gofpeley Island | Raja Ampat | 0.82 km² | — | 17 m |
| Gofur Island | Aru Islands Regency | 0.01 km² | — | — |
| Golden Island | South Australia | — | — | 37 m |
| Goldsmith Island | Queensland | — | — | 70 m |
| Goler Island | Aru Islands Regency | 0.15 km² | — | — |
| Gomanin Island | Aru Islands Regency | 0.28 km² | — | — |
| Gonabarabara Island | Milne Bay Province | 0.24 km² | — | — |
| Goodenough Island | Milne Bay Province | 687 km² | 19,625 | 2,536 m |
| Goods Island | Queensland | 2.14 km² | 0 | 31 m |
| Goodwin Shoal | Queensland | — | — | 8 m |
| Goodwood Island | Harwood | — | 91 | — |
| Goold Island | Queensland | — | — | 282 m |
| Goonaburoo Island | South Australia | — | — | 51 m |
| Gooninnah Island | Northern Territory | — | — | 17 m |
| Goose Island | Tasmania | 109 km² | — | 11 m |
| Goose Island | South Australia | — | — | 4 m |
| Goose Island | South Australia | — | — | 10 m |
| Goose Neck Island | Otago Region | — | — | 362 m |
| Gorangai Island | Aru Islands Regency | 5.44 km² | — | — |
| Goras Island | Fakfak | 0.01 km² | — | 11 m |
| Gore Island | Queensland | — | — | 13 m |
| Goria Korbaya Island | Aru Islands Regency | 0.00 km² | — | — |
| Goriaga Island | Aru Islands Regency | 0.09 km² | — | — |
| Goriaga Island | Aru Islands Regency | 0.00 km² | — | — |
| Gorikomnar Pot Island | Aru Islands Regency | 0.00 km² | — | — |
| Gorinerlou Island | Aru Islands Regency | 0.02 km² | — | — |
| Gorom Island | Eastern Seram | 66.1 km² | — | 183 m |
| Goso Island | Raja Ampat | 1.03 km² | — | 10 m |
| Goson Palay Island | Raja Ampat | 0.00 km² | — | — |
| Gosong Bago Matlolo Island | Raja Ampat | 0.00 km² | — | — |
| Gosong Bago Sawi Island | Raja Ampat | 0.00 km² | — | — |
| Gosong Balak Island | Raja Ampat | 0.00 km² | — | — |
| Gosong Balak Island | Raja Ampat | 0.00 km² | — | — |
| Gosong Ganan Island | Raja Ampat | 0.00 km² | — | — |
| Gotanhundi Island | Aru Islands Regency | 0.09 km² | — | — |
| Gould Island | Queensland | — | — | 10 m |
| Gourd Island | New South Wales | — | — | 2 m |
| Governor Island | Tasmania | 2 km² | — | — |
| Gowack Island | New South Wales | — | — | 3 m |
| Grace Lea Island | New South Wales | — | — | 1,154 m |
| Graham Island | Northern Territory | — | — | 17 m |
| Grand Junction Island | South Australia | — | — | 26 m |
| Granite Island | South Australia | 0.25 km² | 0 | 30 m |
| Grant Island | Northern Territory | — | — | 5 m |
| Grantham Island | South Australia | — | — | 30 m |
| Grants Island | Queensland | — | — | 14 m |
| Grass Island | Queensland | — | — | 6 m |
| Grasshopper Island | New South Wales | — | — | 3 m |
| Grassy Island | Queensland | — | — | 135 m |
| Grave Island | Tasmania | — | — | 18 m |
| Gravididam Delapan Island | Kaimana | 0.00 km² | — | — |
| Gravididam Dua Island | Kaimana | 0.00 km² | — | — |
| Gravididam Empat Island | Kaimana | 0.00 km² | — | — |
| Gravididam Enam Island | Kaimana | 0.00 km² | — | — |
| Gravididam Lima Island | Kaimana | 0.00 km² | — | — |
| Gravididam Satu Island | Kaimana | 0.00 km² | — | — |
| Gravididam Sembilan Island | Kaimana | 0.00 km² | — | — |
| Gravididam Tiga Island | Kaimana | 0.00 km² | — | — |
| Gravididam Tujuh Island | Kaimana | 0.00 km² | — | — |
| Great Barrier Island | Auckland Region | 285 km² | 939 | 627 m |
| Great Barrier Reef | Queensland | 348,000 km² | — | — |
| Great Dog Island | Tasmania | 3.75 km² | — | 22 m |
| Great Glennie Island | Victoria | — | — | 13 m |
| Great Island | Southland Region | 7.36 km² | — | 185 m |
| Great Palm Island | Aboriginal Shire of Palm Island | 55 km² | 2,098 | 428 m |
| Great Woody Island | Queensland | — | — | 29 m |
| Greater Pyramidal Rock | Tasmania | — | — | 126 m |
| Green Island | Queensland | 0.15 km² | 0 | 14 m |
| Green Island | Queensland | — | — | 17 m |
| Green Island | Queensland | — | — | 2 m |
| Green Island | New South Wales | — | — | 25 m |
| Green Island | New South Wales | — | — | 1 m |
| Green Island | New South Wales | — | — | 5 m |
| Green Island | New South Wales | — | — | 294 m |
| Green Island | Northern Territory | — | — | 2 m |
| Green Island | Tasmania | — | — | 75 m |
| Green Island | Tasmania | — | — | 25 m |
| Green Island | Tasmania | — | — | 1 m |
| Green Island | Victoria | — | — | 129 m |
| Green Island | Victoria | — | — | 2 m |
| Green Island (Ōkaihae) | Otago Region | 0.04 km² | — | — |
| Green Islet | Queensland | — | — | 14 m |
| Green Tree Island | Tasmania | — | — | 304 m |
| Greenhill Island | Northern Territory | — | — | 16 m |
| Greenly Island | South Australia | — | — | 45 m |
| Greens Island | New South Wales | — | — | 11 m |
| Greenwood Island | Northern Territory | — | — | 5 m |
| Gregorys Bar | Northern Territory | — | — | 93 m |
| Griffiths Island | Victoria | 31 km² | — | 5 m |
| Grindal Island | South Australia | — | — | 23 m |
| Grindstone Island | South Australia | — | — | 6 m |
| Groote Eylandt | East Arnhem Region | 2,285 km² | 1,539 | 219 m |
| Groper Island / Tatapihi | Auckland Region | — | — | 39 m |
| Grose Island | Northern Territory | — | — | 6 m |
| Grose Island | Northern Territory | — | — | 3 m |
| Gual-Guali Diko Island | Aru Islands Regency | 1.70 km² | — | — |
| Guari Island | Aru Islands Regency | 0.00 km² | — | — |
| Guarifanu Island | Aru Islands Regency | 0.02 km² | — | — |
| Gubbubuil Island | Aru Islands Regency | 0.00 km² | — | — |
| Guerard Island | Victoria | — | — | 19 m |
| Guernsey Island | Queensland | — | — | 9 m |
| Gulanefafan Island | Tanimbar Islands | 0.40 km² | — | — |
| Gulanivavan Timur Island | Tanimbar Islands | 0.21 km² | — | — |
| Gulewa Island | Louisiade Rural LLG | 0.59 km² | — | — |
| Gull Island | South Australia | — | — | 2 m |
| Gull Rock | Tasmania | — | — | 1 m |
| Gull Rock | Tasmania | — | — | 2 m |
| Gulpa Island | New South Wales | — | — | 104 m |
| Guluwuru Island | Northern Territory | — | — | 32 m |
| Gum Island | Queensland | — | — | 272 m |
| Gumbrell Island | Queensland | — | — | 17 m |
| Gumlell Island | South Australia | — | — | 19 m |
| Gumly Gumly Island | New South Wales | — | — | 185 m |
| Gunbower Island | Victoria | — | — | 89 m |
| Gungwiya Island | Queensland | — | — | 25 m |
| Gunn Island | Queensland | — | — | 16 m |
| Gunungapi Island | Maluku | 7.31 km² | — | 640 m |
| Gurat Island | Aru Islands Regency | 0.00 km² | — | — |
| Guri Island | Jayapura | 0.00 km² | — | — |
| Guriakarbayol Island | Aru Islands Regency | 0.23 km² | — | — |
| Guridaudau Island | Aru Islands Regency | 0.00 km² | — | — |
| Gurifanu Island | Aru Islands Regency | 0.03 km² | — | — |
| Gurija Gwa Gwa Barat Island | Aru Islands Regency | 0.02 km² | — | — |
| Gurija Gwa Gwa Island | Aru Islands Regency | 0.14 km² | — | — |
| Gurija Gwa Gwa Tengah Island | Aru Islands Regency | 0.01 km² | — | — |
| Gurija Gwa Gwa Utara Island | Aru Islands Regency | 0.03 km² | — | — |
| Guryap Barat Island | Teluk Bintuni | 55.8 km² | — | — |
| Guryap Timur Island | Teluk Bintuni | 25.2 km² | — | — |
| Gwadrom Island | Aru Islands Regency | 0.00 km² | — | — |
| Gwakura Island | Northern Territory | — | — | 31 m |
| Gwariabanban Island | Aru Islands Regency | 0.00 km² | — | — |
| Gwariadeldeli Selatan Island | Aru Islands Regency | 0.00 km² | — | — |
| Gwariadeldeli Utara Island | Aru Islands Regency | 0.00 km² | — | — |
| Gwariafungfungan Dum Island | Aru Islands Regency | 0.00 km² | — | — |
| Gwariafungfungan Lim Island | Aru Islands Regency | 0.01 km² | — | — |
| Gwariafungfungan Ot Island | Aru Islands Regency | 0.00 km² | — | — |
| Gwariafungfungan Rua Island | Aru Islands Regency | 0.00 km² | — | — |
| Gwariasian Island | Aru Islands Regency | 0.02 km² | — | — |
| Gwarifaten Island | Aru Islands Regency | 0.01 km² | — | 12 m |
| Gwarigumguman Island | Aru Islands Regency | 0.00 km² | — | — |
| Gwarija Kangkana Island | Aru Islands Regency | 2.11 km² | — | — |
| Gwarikabal Island | Aru Islands Regency | 0.00 km² | — | — |
| Gwarikat Island | Aru Islands Regency | 0.00 km² | — | — |
| Gwaringarngar Island | Aru Islands Regency | 0.01 km² | — | — |
| Gwarla Juring Island | Aru Islands Regency | 1.84 km² | — | — |
| Gwasir Island | Aru Islands Regency | 0.16 km² | — | — |
| Gwuardrom Island | Aru Islands Regency | 0.72 km² | — | — |