Tales to Astonish#1(1959)

Captain Kane navigates his fishing vessel through the sea. His crew's fishing nets manage to ensnare a lobster nearly twelve feet in length. Kane reports the phenomenon to one of his guests, Professor Briggs. This is the second of such bizarre creatures that the crew has discovered. As Kane goes into Briggs' cabin, he finds the Professor studying the remains of a four-foot starfish. Briggs is convinced that this strange mutated sea life is related to his old colleague Doctor Parker - a scientist who disappeared over a decade ago. Briggs has a copy of a map that Parker charted before he disappeared. At the professor's request, Captain Kane sets a course for this mysterious hidden area of the sea. As they follow Parker's map, the ship collides with a giant green mountain that wasn't indicated on the chart. Kane and Briggs manage to rope together two oil barrels and use them as a flotation device, but the rest of the crew is lost. The two men come to an island. They discover a tribe of natives surrounding a massive wooden barricade. In front of the barricade is Doctor Parker tied to a post. The natives capture Kane and Briggs and secure them as well. Parker tells them that he has been experimenting with a hormone regulator serum. He tested the serum on several specimens, but could not control the animals' growth. The product of Parker's work makes its presence known as a giant snapping turtle bursts through the outer side of the barricade. This is Experiment 247. As natives flee in terror, the three men manage to free themselves and make for an inlet where Doctor Parker has a motor launch secured. Parker tells them that Experiment 247 is actually the second of such trials he has conducted. The original project, Experiment XYZ, was conducted years earlier. Kane and Briggs soon realize that Experiment XYZ is actually an even larger turtle, and was also the "mountain" responsible for scuttling Kane's ship. The massive creature is too large to even notice the three men, who safely race away.