A harmless Garter snake resting near the river (Thamnophis sp.).
If you can identify the exact specie of Garter snake, please post a comment or email me.
Most likely a subspecies of Western Terrestrial Garter Snake (Thamnophis elegans).
Photo taken during a 3-day trek on the Pine Ridge trail to the Sykes Hot Springs in the Vantana Wilderness, near Big Sur (California)