Underwater Dolphin Escape

You are very fond of diving, because the underwater depths, you can find the remains of ancient civilizations that disappeared under the water. Recently, scientists have found a city in the underwater depths, and you were allowed to dive in this place. Here you put your gear and plunged into the water. Really a very beautiful city, but all of a sudden, you find a dolphin who fell into the trap. You need to find a way that will help release the poor animal.