Wario Land 3: Part 60: Beneath the Waves (Gray Chest)

Description:

The player has collected four of five Music Boxes and unlocks an aquatic level called Beneath the Waves. They must navigate currents, use a high jump to reach a Gray Key, and then use zipline pulleys to access a Gray Chest. The chest contains an Explosive Plunger Box, which detonates to create Bomb Blocks that open new paths in other levels.