Aquaman #2 (1962)

Aquaman and Aqualad embark on a thrilling adventure in Aquaman #2 (1962) as they search for two treasures for Captain Sykes to secure the release of a captured ship. They encounter Captain Sykes on his ship, the S.S. Seahawk, who holds the Vulcan and her crew hostage as leverage for Aquaman and Aqualad to retrieve two ancient relics for his "maritime collection". With a map provided by Captain Sykes, Aquaman and Aqualad locate the first relic, hidden inside an enormous coral mountain. As they break through the final barrier to retrieve the relic, an unknown gas is released, making some of the fish giant and agitated. Aqualad fights the giant fish but turns on Aquaman, growing in size and becoming agitated as well. The danger passes, and Aqualad returns to normal size and sanity. Aquaman retrieves the first relic from the broken coral cavern and receives another map indicating the location of the second artifact on Pecos Island. As they approach Pecos Island, a sea serpent surfaces from beneath the waves, driving the heroes away. Aquaman summons hundreds of fish to form a tunnel to the shore, and they swim to the island undetected. But the sea serpent pursues them, rampaging through the docks and boats lining the shore. Aquaman and Aqualad are then taken prisoner by the native islanders. They seek the wailing shell, the second relic, which was created by a powerful wizard to keep the sea serpent at bay. The tribal leader releases Aquaman, but not Aqualad, and Aquaman eventually retrieves the shell by provoking the sea serpent to move beyond the island's coastal waters, breaking the spell that kept it bound to the island. Aquaman refuses to give up the relic until Captain Sykes releases the Vulcan hostages. The adventure ends as the Vulcan sails away to safety, and Aquaman and Aqualad continue their underwater adventures.