These were soooo cool. The big submarine - it was supposed to be the U.S.S. Nautilus, the world's first atomic sub - and the larger frogmen came first and were items you had to send away for from Kellogg's. The smaller ones came later and were stuck in cereal boxes. You put baking powder in the conning tower of the sub and in the conical left foot extensions of the frogmen, then drop them into a goldfish bowl or other container of water. The baking powder would make a bubble that would bring the toy to the surface, it would escape and the toy would sink to the bottom again and on and on. I remember being in the third grade when I got the sub. The frogmen came later.