It is part of the Australasian realm, which includes neighboring New Caledonia and the Solomon Islands, as well as Australia, New Guinea, and New Zealand.

Nendö reaches over 500 meters elevation, and Utupua 350 m. They are made mostly of basaltic volcanic rocks of Pliocene origin, less than 5 million years old.

[6] Smaller islands in the group include Tinakula (8 km2 and 800 meters elevation), a conical active stratovolcano 30 km north of Nendö, and the Reef Islands northeast of Nendö, composed of uplifted Pleistocene reef limestone and rising only 5 meters above sea level.

Typical species include Campnosperma brevipetiolatum, Calophyllum vitiense, Gmelina salomonensis, Maranthes corymbosa, Falcataria falcata, Pterocarpus indicus, and Endospermum medullosum.

[2] Agathis macrophylla grows only on Nendö and Vanikoro, and is found on ridges and slopes as an emergent tree in mixed forests or in monotypic stands.

They include the conifers Agathis macrophylla and Dacrycarpus imbricatus, together with broadleaf evergreen trees Metrosideros vitiensis, Syzygium spp., Pterophylla spp., Geissois spp., Quintinia spp., and Ascarina spp.

[2] The tree ferns Cyathea and Dickinsonia are common, and the endemic palm Clinostigma harlandii is found on the islands Ambrym, Aneityum, and Erromango.

It is a large emergent tree in lower montain rainforest on the wetter western and northwestern slopes of Espiritu Santo's central mountain range, with an average annual rainfall of about 4,500 mm.

[2] Littoral forests include Casuarina equisetifolia, Pandanus spp., Barringtonia asiatica, Terminalia catappa, Hernandia spp., and Thespesia populnea.

It is unique among Boidae snakes for its “bevel” or “spade”-shaped snout, used for digging; perhaps the closest comparable species would be the Kenyan sand boa, which spends much of its time burrowing, where it will lie in wait to ambush its passing prey above.

Fifteen species are endemic – Vanuatu scrubfowl (Megapodius layardi), Santa Cruz ground-dove (Gallicolumba sanctaecrucis), Tanna ground-dove (Gallicolumba ferruginea), Tanna fruit-dove (Ptilinopus tannensis), Baker's imperial pigeon (Ducula bakeri), palm lorikeet (Charmosyna palmarum), chestnut-bellied kingfisher (Todirhamphus farquhari), Vanikoro monarch (Mayrornis schistaceus), buff-bellied monarch (Neolalage banksiana), black-throated shrikebill (Clytorhynchus nigrogularis), Vanikoro flycatcher (Myiagra vanikorensis), Santa Cruz white-eye (Zosterops santaecrucis), yellow-fronted white-eye (Zosterops flavifrons), Sanford's white-eye (Woodfordia lacertosa), New Hebrides honeyeater (Phylidonyris notabilis), royal parrotfinch (Erythrura regia), Polynesian starling (Aplonis tabuensis), rusty-winged starling (Aplonis zelandica), and Mountain starling (Aplonis santovestris).