One ROV got a saw lodged in the side of the leaking riser pipe in early June, for example, causing BP to rethink its strategy for trying to stop the gushing leak.
The joints between the half-pipes have rubber seals to stop the contents leaking, and each half-pipe has a vertical pipe connected to it, to introduce or dispose of the fluid concerned.
Video shot by the robotic submarines (a.k.a. remote operated vehicles or ROVs) seems to indicate that oil is leaking from three spots in a pipe that is laying on the seafloor.