Tentalus

Tentalus is a boss creature featured in Skyward Sword. When Link tries to go to the control room on the Sandship, Tentalus appears and nearly destroys the whole ship. Link has to fight it to get Nayru's Flame to temper the Master Sword.

Battle
After opening the door to the power room, the battle begins. Link must make his way to the deck of the Sandship. However, most of the ship has been destroyed and there are tentacles in the way. In order to clear the way, Link must destroy the tentacles with a Skyward Strike. After reaching the deck, Tentalus appears. First, Link must avoid its tentacles and continue removing them with Skyward Strikes. Once several tentacles have been removed, Tentalus will surface and attempt to damage Link with its arms. Link must shoot its eye with an arrow, stunning it. While it is stunned, Link can attack it directly with his sword, and he can also cut off its "hair" to receive arrows and hearts. After enough damage has been dealt, Tentalus will break part of the deck causing barrels to fall towards Link, and causing a crate to fall from the higher level of the deck. Using the crate, Link must climb up to the upper level, where the battle contiues.

Tentalus will continue to attack in much the same manner and is damaged in the same way. However, instead of attacking with its tentacles from below, it will attack with its toothed "hair." They must be dealt with by quickly slashing. Once Tentalus has been defeated, Link will be rewarded with a Heart Container and Nayru's Flame.