The Philippine sailfin lizard is notable not only for its impressive size of up to a metre in length, but also for its rather spectacular appearance. Adults of this large mottled greenish-grey lizard boast a well-developed crest of tooth-like scales from the nape of the neck down the back. However, the most distinctive feature of adult males is the erect ‘sail’ of skin at the base of their tail, up to 8 cm high, which provides propulsion for this strong swimmer to move through the water, and probably also plays an important role in territorial display and thermoregulation. Another adaptation to its watery environment is the large, flattened toes that help the lizard to swim, and even enable it to ‘run’ across the water’s surface, observed particularly in the lighter juveniles.