USS John Muir

From Memory Alpha, the free Star Trek reference.

The USS John Muir (NCC-1732) was a Federation starship in service during the late 23rd century.

In 2293, it was undergoing a refit at Starbase 24 during the time Operation Retrieve was proposed. (Star Trek VI: The Undiscovered Country)

The John Muir was named after the renowned environmental advocate who was largely responsible for the creation of Yosemite National Park. The ship itself was not mentioned in dialog, but was listed on a starship status display that was seen on the Enterprise-A. The information comes from the Star Trek Concordance.