Martha Lake is located within Kings Canyon National Park, where it sits on the Le Conte Divide southwest of Mount Goddard. The lake serves as the source of the south fork of the San Joaquin River and provides access to Hell for Sure Pass via what is considered the easiest route.

The lake's high alpine environment creates unique conditions for paddlers. Due to its elevation, Martha Lake can remain frozen well into the summer months, with complete ice coverage possible even in August. This makes seasonal timing critical for any paddling plans.

The lake's outflow creates the beginning of a whitewater section that extends approximately 5 miles to the northwestern boundary of Kings Canyon National Park. This downstream section features Class III-IV rapids, with potential Class V conditions during higher flows. The ideal flow range for the river section is between 500-1500 cubic feet per second.

Access requires proper permits for overnight stays within Kings Canyon National Park, and visitors must follow Leave No Trace principles. The area around Martha Lake offers views of surrounding peaks including Mount Reinstein, providing a dramatic backdrop for paddling excursions.

For paddlers considering this destination, it's important to note that the high elevation and remote location require careful preparation and consideration of weather conditions. Flash floods are possible during heavy rainfall periods, adding an additional safety consideration for those planning to paddle either the lake or its outflow.