Lake Rocky (ロッキーのうみ Rokkī no Umi?, lit "Rocky Sea") is the fourth level in Tails Adventure for the Sega Game Gear, coming after Polly Mountain and before Cavern Island. Though thanks to the non-linear nature of Tails Adventure, the young fox must return to the region on various occasions as new items (like the Anti-air Missile and Mine) open up new routes.
Having acquired the Vulcan Cannon component from the Kukku army on Polly Mountain, Tails is finally able to bring the Sea Fox submarine up to combat readiness. Now the outlying islets off the coast of Cocoa Island proper can be explored. Launching of from the pier outside Tails' House, the intrepid fox takes to the waves; although predictably the Battle Bird Armada got there first.
"Lake" Rocky is a coastal shoreline riddled with submarine caverns - and no shortage of mines, dropped all over the place by the avian invaders. In his first visit to the level, Tails simply sails right through to Cavern Island, but there are numerous different nautical routes leading to different offshore areas. The seawater turns eutropified viridian around the entrance to Lake Crystal, and the downwards path leading to the Battle Fortress is crammed full of guns and mine chutes.
After Tails has been to Cavern Island and picked up the Anti-air Missile, Lake Rocky's boss becomes accessible. Further out in the open ocean, Tails takes on a Kukku anti-submarine cruiser. The bird-brained sailors lob depth charge after depth charge into the waters, as the Sea Fox responds with a barrage of missiles into the ship's underside.
- Despite being referred to as a lake in the English version of the game, Lake Rocky is actually the sea located south of Cocoa Island.
- There are no items available in Lake Rocky.