Lake Crystal is a level in Tails Adventures for the Sega Game Gear. Following in the style of its dubiously-translated predecessor Lake Rocky, Lake Crystal is not a lake at all, but rather Cocoa Island's central river. After obtaining the Sea Fox's Extra Speed upgrade from Green Island, Tails can power his way up the river rapids all the way to the headwaters, flowing out of the Polly Mountains.
This level sees Tails' submarine hopping its way upriver through shallow waters that don't even require submersion. Tails travels against the current as large logs flow downstream. These logs must be jumped over in order to avoid taking damage. On occasion, fleet-footed Battle Kukku troops ride with the logs, requiring swift action with the Vulcan Gun or Proton Torpedo to dislodge them.
The stage is divided into two sections, separated by a huge waterfall at the end of the first. In order to clear it, the Sea Fox has to activate its Extra Speed engines and jump at the very last instant to get enough height. The second section of Lake Crystal is generally easier than the first, with most of the logs being replaced by overhead bird bombers, whose payloads are less tricky to evade.
There are no items available in Lake Crystal.