The Other 50% Reef
The reef is close to Luke's Reef, a similar reef that Luke discovered when he fell overboard on his captain's ship, The Inebriated. Like Luke's reef, The Other 50% Reef consists almost entirely of a species of extremely spiky coral. However, it is considerably taller, nearly reaching a ship's hull.
When Luke fell overboard, he was thrown a rope by his crew, which he clung to as the ship continued on its course. When the ship passed over the reef, Luke was caught on the spiky coral, costing him the left half of his body. The reef was then given its name by The Inebriated's crew and is still labelled so on their maps today.