Key points about Mongolia and its "navy":
Landlocked status:
The primary reason Mongolia doesn't have a traditional navy is that it has no coastline and is entirely surrounded by land.
Lake Khovsgol boat:
A small tugboat named "Sukhbaatar" operates on Lake Khovsgol, sometimes mistakenly considered the "Mongolian Navy," but its main function is cargo transport, not military action.
Historical context:
During the Mongol Empire under Kublai Khan, Mongolia did have a large navy, but most of it was destroyed during attempted invasions of Japan.