Small snake, maximum length of 114 cm (average between 50 and 90 cm). Flattened body, with very small square or hexagonal-shaped scales along the body. The coloration varies, but the dorsal part is generally black and the ventral and lateral regions are generally yellow. The tail is usually light colored with black spots. The tail is modified to swim. This is the only sea serpent in the country.

The pelagic snake, usually found 1 - 20 km from the Pacific coast, it cannot be found in the Atlantic. It feeds off small fish. Found in tropical and subtropical seas.