The Sea King was leader of the sea giants outside of Vol'jins first base camp on the Echo Isles. He guarded pyres that Rexxar, Rokhan and Chen Stormstout lit to alert the troll forces on that island to head out to the mainland.
The giant known as the Sea King was a very powerful sea giant who came to lead the sea giants surrounding the Echo Isles. He found the axe, Killmaim, after it had been thrown into the sea by Dethorin.
The Sea King was met by Rexxar and his band of adventurers, but the tenacity of Rexxar and his kin were more than the Sea King could handle, and he was defeated.