An eight is a rowing boat used in the sport of competitive rowing. It is designed for eight rowers, who propel the boat with sweep oars, and is steered by a coxswain, or cox.

Each of the eight rowers has one oar. There are four rowers on the stroke side (rower's right hand side) and four on the bow side (rower's lefthand side). The cox steers the boat using a rudder and is normally seated at the stern of the boat. Because of the speed of the boat, it is generally considered unsafe to row coxless or to have a bowloader cox.

Racing boats (often called "shells") are long, narrow, and broadly semi-circular in cross-section in order to reduce drag to a minimum. Originally made from wood, shells are now almost always made from a composite material (usually carbon-fibre reinforced plastic) for strength and weight advantages. Eights have a fin towards the rear, to help prevent roll and yaw and to help the rudder. The riggers are staggered alternately along the boat so that the forces apply asymmetrically to each side of the boat. If the boat is sculled by rowers each with two oars the combination is referred to as a octuple scull. In a scull boat, the riggers apply forces symmetrically. A sweep oared boat has to be stiffer to handle the unmatched forces, and so requires more bracing, which means it has to be heavier and slower than an equivalent sculling boat. However octuple sculls are not used in main competitions.