Porter is concerned that Bud is taking old Hap Gorman's stories too seriously and warns his son that not everything the old man tells him is true.

Despite their best attempts to impress a visiting Congress woman, Porter and the boys are devastated to learn that she plans to close the park.

In a last ditch attempt to convince Congress woman Helen Browning that she should use government funding to keep the Park open, Sandy and Bud take her skin-diving.

Bud and Sandy, on a trip with Hap Gorman to his secret fishing grounds, board an abandoned boat, not knowing that a hidden charge of dynamite is about to blow it to pieces.

When Flipper finds a Spanish doubloon on the ocean bottom and brings it to Bud and Sandy, rumours about Spanish Treausures spread quickly and an underwater gold rush ensues.