Varanus rasmusseni is a member of the V. salvator species group. In 2010 KOCH et al reviewed the Varanus salvator complex on the Philippine Islands and described this new species. It belongs to the subgenus Soterosaurus, which was derscribed by ZIEGLER & BÖHME (1997).
The Rasmussens Water Monitor is a bulky monitor and can grow up to a total length of about 150 cm.
The tail in this species is laterally compressed and shows a distinct dorsal double keel. The animals are adapted to water. The tail is about 1.6 times the SVL.

The distribution of V. rasmusseni is only known from the Tawi-Tawi Island within the Sulu Archipelago, but also some smaller island nearby are inhabitat, like Siasi, Sanga-Sanga, and Bongao (KOCH et al. 2010).

There is no report on captive husbandry published till now.