Sea Speller is a game where you control a dolphin helping a submarine reach the ocean floor before it runs out of air. The player's task is to pick up "letter sponges" scattered along the sea bottom, matching them with signs on the sub's billboard to create words. Every complete word lights up another light on the submarine, and once they're all lit up, it descends to deeper waters for the next level.
The quicker you are, the higher your score - if the sub reaches the bottom with air left over, a bonus is awarded; you can save time by using single letter combinations to create more than one word. Certain "magic words" will automatically send you to the next level to really speed things along. In addition to the single-player mode, two players can play cooperatively (for a shared score) by taking turns.
Sea Speller was released for the Commodore 64 in 1970. It is an Educational game that challenges your spelling skills and reaction time.