Fantastic Four #97 (1961)

At the request of the U.S. Navy, the Fantastic Four investigate mysterious disappearances of ships off the Florida coast! A local legend says that a sea creature patrols the waters wreaking havoc! Could that be true? With help from a skilled aquarium worker, Reed, Ben, and Johnny explore the deep waters of the lagoon! But near the floor of the lagoon, the aquarium worker turns traitor!