The cannon is a weapon in The Precursor Legacy. It is a primitive turret used by the Lurkers at Sentinel Beach and Misty Island. It has a simple wooden frame and uses big gears to rotate the cannon or move it up and down. The cannon itself is large, and has a bell-shape without any specific details. They are operated by babaks.
It has a relatively low firing rate and the explosives take a few seconds to explode. Its main use for Jak is not to kill enemies though, but instead to destroy the strong boxes. The explosives consists of a cloth bag with a fuse tied around the end.
The first cannon seen is at Sentinel Beach on top of a large tower only accessible through blue eco vents placed along a few towering islets. It faces the beach and can often be found showering the beach area with explosives until Jak stopped the lurkers operating it in the "Launch up to the cannon tower" mission.
The second one is atop the construction between the bay and the dark eco silo at Misty Island, only accessible by a long wooden scaffolding leading upwards. This path begins at the Lurker ship and is impeded by a continuous barrage of big logs rolling down. The cannon itself is mainly focused on trying to open the big dark eco silo keeping Gol and Maia from the dark eco inside it, Samos Hagai wanted Jak to stop it in the "Stop the cannon" mission.