Sewers Skip is a skip in Jak 3 which allows the player to obtain a checkpoint midway through the mission 'Reach Metal Head area via sewer' and skip any missions before it in the mission tree. It is only used in Hero Mode All Bosses.
In Jak 3, each section of the sewers and its checkpoints are stored in a different level file. There is also another level file, 'sewa', which is shared between all sewers levels, containing all of the elevators. However, likely due to a mistake, 'sewa' also contains a trigger which sets the player's checkpoint to 'sewh-checkpoint', which is partway through the mission 'Reach Metal Head area via sewer', in an area which should not normally be accessible before the mission takes place. By going near an elevator to load in 'sewa', and going out of bounds to pass through the trigger, the player can then die and Jak will respawn at the otherwise inaccessible area, allowing several missions to be skipped.
Sewers Skip was discovered by BurkeMaverick on July 5th, 2020.