The head, back, and sides have a marbled or reticulate pattern of dark blotches on a light brown or brassy-colored background.

[6] A female coastal giant salamander will lay her eggs in moderate to slow flowing mountain streams under rocks and crevasses, hatching in early to mid spring.

The coastal giant salamander, being a member of the genus Dicamptodon, exhibits two distinctive phases within its life; an aquatic larval stage with filamentous gills and an elongated tail with a caudal fin (similar to that of a tadpole), and a terrestrial adult form losing their caudal fin and filamentous gills, and instead developing robust legs and a pair of internal lungs.

[7] Some coastal giant salamander larvae continue to grow into adults and become sexually mature without losing their external gills.

Terrestrial adult coastal giant salamanders spend most of their time underground in burrows, emerging to reproduce and forage on rainy and humid nights.

The coastal giant salamander is endemic to the Pacific Northwest, found in Northern California, Oregon, Washington, and southern British Columbia.