The Long Fissure is a landmark in the Zahhab Region in Endless Ocean 2. As its name suggests, it is a long crack in the rocky seafloor that leads out to the edge of the cliff that brings the player to the Open Sea.
The player first discovers this landmark the second time they go diving in the Zahhab Region. When searching for the Pacifica Treasure's final resting place, it is revealed on Nineball Island using the dragon flute and a map of the circular Earth found in Valka Castle that this fissure leads to the "queen's tomb." This turns out to be true, as looking through the largest gap in the fissure in the ocean floor reveals some sort of cave. However, the player cannot enter through the Long Fissure, as the gap is too small, and must instead enter through the Echoing Terrace, which the Long Fissure points to.
The local sea life includes several Green Sea Turtles and several shoals of smaller fish. As well as this, the oversized Whale Shark that the player first sees while investigating the nearby Mushroom Rock also makes its rounds near this area, and all of the small fish that accompany it go along.