Sonic the Hedgehog/Labyrinth

Labyrinth Zone is a ruin-like maze partially submerged in water. It features many spikes and water-driven contraptions. The greatest hazard of this zone is not the enemies or the traps, but the water. Sonic, being a hedgehog, is terrible at swimming. After staying underwater for a limited amount of time (18 seconds, with warning bells after 5, 10, and 15 seconds) a countdown starts (5 breaths/about 12 seconds), at the end of which Sonic drowns. This would lead the player to a great sense of panic at the sound of the countdown music. Collecting air bubbles found in certain points resets the counter and prevents Sonic from drowning. At the end of Act 3, Sonic has to follow Dr. Robotnik through an ascending passage filling with water. Robotnik's craft can be destroyed; however, this is extremely hard without use of cheats and is not required to complete the level, nor does it offer any sort of bonus.