The overlooked sloops and survey ships of naval history

What is the most underrated warship in history, and why?

Sloops and survey ships are strong candidates because their dangerous mapping and access work enabled campaigns and maritime expansion without receiving battleship-level fame.

The 64-gun ships receive less attention than the better-known 74s, while small sloops and survey vessels are easy to overlook. Survey crews charted dangerous coasts where an unknown reef could destroy their ship far from realistic rescue. Mapping those waters gave later fleets and merchant ships safer access. One suggested example is Captain Cook's contribution to the British movement up the St. Lawrence toward Quebec. Ships with modest fighting power could enable major operations through the navigational information they gathered.