It has rugged terrain, reaching up to Mount Gharat (797 m), the peak of the active stratovolcano which lies at the center of the island.

[1] Most of the island is covered by the Santa Maria Pyroclastic Series, a mafic ignimbrite unit that was produced by the eruption that formed the caldera.

[2] Gaua is rare in hosting a mafic ignimbrite, as most similarly explosive eruptions are more silicic; other examples include Masaya in Nicaragua,[3] and on Ambrym,[4] and Tanna,[5] also in Vanuatu.

The eruption of the SMPS was also associated with the activation of ring faults, and the production of parasitic volcanic cones around the upper slopes of the volcano.

The eastern side has a few hamlets with an immigrant community, the members of which have come from the two smaller islands Merig and Merelava, that lie southeast of Gaua.

Other Torres-Banks languages that have reflexes of the two etyma include Mwotlap Agō [aˈɣʊ] and Alkon [alˈkon];[9] and Vurës Gō [ɣo] and Lokon [lɔˈkɔn].

Thus it is called Gog [ɣɔɣ] in Nume, Gō [ɣʊ] in Koro (both < *ɣaua), and Lkon [lkɔn] in Dorig (< *laᵑgona).