Nasmyth is a lunar impact crater located near the southwestern limb of the Moon.

It is attached to the southeast rim of the flooded crater Wargentin, and the southern half is overlain by the larger Phocylides.

The floor has been flooded by lava flows in the past, making the surface relatively flat and the rim low.

There is no central peak within the crater, but the floor is impacted by some small craterlets.

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Nasmyth.