In 1974 a governmental committee examined the environmental impact of mining and other commercial activities and advised on measures to protect the island.

[1] Christmas Island consists of an uplifted limestone cap metamorphosed from coral reefs overlying more ancient volcanic andesite bedrock.

[4] The underlying seamount lies some 500 km (310 mi) southwest of Indonesia, and the isolation by the abyssal zone has led to endemism amongst the marine ecosystem.

Both the waters surrounding the island and its land surface are fecund, and the park exhibits a high level of biodiversity with many endemic species.

The bright red carapaces and sheer density of crabs make their routes to the sea observable from the air.

Nonetheless, the populations of red crabs are threatened by the arrival of the invasive yellow crazy ant (Anoplolepis gracilipes).

[8] There are six species of reptile native to the park, of which five are endemic:[2] the giant gecko (Cyrtodactylus sadlieri), the Christmas Island gecko (Lepidodactylus listeri), the forest skink (Emoia nativitatis), the blue-tailed skink (Cryptoblephanus egeriae) and the Christmas Island blind snake (Ramphotyphlops exocoeti).

[2] A further five species of reptile have been reported, but all were introduced by human activity: the barking gecko (Hemidactylus frenatus), house gecko (Gehyra mutilata), black blind snake (Ramphotyphlops braminus), wolf snake (Lycodon aulicus capucinus) and grass skink (Subdoluseps bowringii).

However, a stand of the normally estuarine mangrove species, Bruguiera gymnorhiza and B. sexangula, is found approximately 50 m (160 ft) above sea level, at Hosnies Spring.