- The River to Sea Relay is an annual team relay run across New Jersey. Originating in Lambertville on the Delaware River and ending at the beach in Manasquan, R2C is a physically and mentally challenging endurance event. Teams consist of 7 runners who will combine to cover the 72-mile distance that passes through 30 towns in Hunterdon, Mercer, Somerset, Middlesex and Monmouth counties. All levels of team participation are welcome as start times are staggered.