Castle on the Sea

Castle on the Sea is an island at the center of the Third Sea that gathers many NPCs with different functions and has no local enemies. The wiki lists an Aura Editor, a Butler, a Sharkman Teacher, a Dark Step Teacher, a Water Kung Fu Teacher, a Martial Arts Master, an Elite Hunter, a Player Hunter, a Mad Scientist, the Sealed King, Sabi, Remove Blox Fruit, Boat Dealers and a Set Home Point, among others. Raids are also done here, and just like in the Second Sea, the Mysterious Scientist is here to buy or trade microchips. Every 75 minutes the Pirate Raid event sends a horde of First Sea and Second Sea enemies at the island; whoever deals the final blow to the tanky last enemy gets a random fruit, and anyone who defeated at least one Pirate receives 100 Fragments when it ends. The raid boss is the Lv. 5000 rip_indra True Form, spawned by pressing the Aura Color buttons with the matching Legendary Aura color and then placing the God's Chalice on the pedestal to the right of the entrance. Three portals lead to Tiki Outpost, the Mansion in Floating Turtle and Hydra Island; the last two require defeating rip_indra True Form once, and the Tiki Outpost portal requires defeating Tyrant of the Skies once.