Drop in the Ocean is the first half of a once-played starting game from the final episode of Takeshi's Castle.
All contestants start at the beach and a helicopter flies over and drops hundreds of coloured balls into the sea. There are eight colours: red, yellow, green, blue, purple, pink, white and black. The colours are later used in the second half of the game, Sandscript, but don't matter in this part. The contestants all have to get a ball for themselves to be able to continue.
Anyone who doesn't manage to get a ball is out of the game.
See Sandscript for the explanation for the second half of the game.