RoboSub is an annual competition held typically held in late July - early August. it encompasses schools from around the world, and tasks them with building fully autonomous underwater robots (AUVs). These robots must perform a wide array of tasks, with the themes of said tasks changing annually. The wide variety of tasks includes Gate, Buoy, Path, Bins, Torpedoes, and Octagon. For more information, visit the RoboSub website.
Gate is a task that require an AUV to pass beneath a submerged "gate" that is moored to the bottom of the environment. As long as the entirety of the AUV goes through the gate between the pillars, the AUV can pass through the gate at any depth.
Path is a task that requires an AUV to follow a set pathway defined by orange markers placed on the bottom of the environment. These markers are placed directly after each of the other tasks, and help guide the AUV towards the next path, in particular Buoy and Bins. For full points, the AUV is supposed to exactly follow the path set by each segment.
Buoy is a task where one or more "buoys" are moored to the floor of the environment, and the AUV is supposed to touch a specific one.
Bins is a task that consists of two bins, each with a separate set of two different objects. 1/3 of each of the bins is covered, requiring the AUV to drop markers into either bin then lift the covering off a bin.
You can read more about the specific rules and tasks for the current year's competition here.