[4] The upper 22 miles (35 km) of Thomes Creek are rated Class IV–V+ ("very difficult") for whitewater kayaking and rafting.

[1][8] Thomes Creek begins at Kingsley Lake, a small pond at elevation 6,460 feet (1,970 m)[9] in the Mendocino National Forest.

[2] The lower part of the creek flows over a wide cobbled alluvial bed composed of coarse gravel and large boulders.

Due to the seasonal nature of precipitation in this area, the lower part of Thomes Creek is often dry during the summer.

[2] Water quality in Thomes Creek is considered good although it has been impacted by high rates of erosion, caused in part by the unstable sedimentary rock that makes up much of the Coast Ranges, but also from human activities such as ranching, logging, agriculture and mining.