Andy swam closer to Mark, finding an irresistible pull to his new friend. Instinctively, Mark coiled his tail around Andy's legs and the men could resist no longer. They kissed passionately, exploring with tongues and hands. Andy felt the merman's cock appear from its protective sheath and rub against his own turgid member. Only separated by the fabric of his pants which were quickly divested.
The two cocks now free rubbed against each other as the two mermen moaned. Andy felt the change accelerating; his legs extended and lost their rigidity. His feet fanned out into fins and merged, the scales spreading to mirror Mark's. He adjusted to coil his tail around his mate's. They frantically rubbed cocks and kissed until they both burst. Filling the water with warm cum.