Containment domes -- These devices, also called coffer dams, are the second of the three major methods BP hopes will eventually stop the leak entirely. Starting with one this week, BP will lower three 40-foot tall containment "domes" over the leaking sections of pipe on the seabed. Some oil will still escape, but the plan is to suck most of it up through the dome (which is actually more of a rectangle). This idea also reveals the essential crudity of our deep-ocean technology: there's nothing subtle about dropping just under a hundred tons of concrete onto a leaking pipe.