If you're a fan of Murphy's Law, you'll appreciate the National Park Service's thorough regulations about safety and back-up equipment.
Perhaps the most important piece of safety equipment is the portable flotation device, required on all river trips. The NPS explains that one of the major reasons for this is the water temperature, which can be 45 to 60 degrees Fahrenheit (about 7 to 15 degrees Celsius). This was not the case for John Wesley Powell, who encountered much warmer water. Since the construction of Glen Canyon Dam in 1963, the water released into the Canyon has been from 200 feet (61 meters) below the top of the dam. This has spelled dangerous conditions for boaters. If you fall into 47-degree Fahrenheit (8-degree Celsius) water, you'll only have about five or 10 minutes of muscle activity to help you survive [source: National Park Service].
Secondly, every trip should have first aid kits in waterproof containers. Recommended items for the kits include antibacterial soap and ointment, Band-Aids, Betadine, gauze, thermometer, and tweezers. In addition, each trip is required to have emergency signaling materials that we'll explain in more detail later on.
The NPS also requires extra oars or paddles on non-motorized boats. Motorized boats have to carry one extra working motor in addition to spare parts, like water pumps, that are prone to break. Motorized boats also need fire extinguishers. Al trips need a boat repair kit, and all inflatable rafts need to carry an air pump.
Finally, you should have maps and river guides with you. The NPS recommends U.S.G.S. Quadrangles or the equivalent.