He did, however, find Pyramid Lake.

This being the body of water into which the Truckee River flows, and the Truckee being the only outlet to Lake Tahoe, it is well that this portion of the account be given in full.
Fremont and Carson were on ahead.

The day was January 10, 1843.
Fremont writes: Leaving a signal for the party to encamp, we continued our way up the hollow, intending to see what lay beyond the mountain.
The hollow was several miles long, forming a good pass (some maps designate this pass as Fremont Pass, others as San Emidio Canyon), the snow deepened to about a foot as we neared the summit.

Beyond, a defile between the mountains descended rapidly about two thousand feet; and, filling up all the lower space, was a sheet of green water, some twenty miles broad (Pyramid Lake).

It broke upon our eyes like the ocean.