She-Ra: Princess of Power (1985)

S1E40 Treasure of the First Ones

When the legendary Mystic Isle breaks the ocean's surface for a single day, Hordak sets his sights on the ancient First Ones' treasure hidden within. Learning of his scheme, Light Hope summons She-Ra, who wastes no time rallying Sea Hawk and his loyal crew to race against the villain and safeguard the relic before it vanishes beneath the waves once more.