Dohyo: Ring
The dohyo (土俵) is the ring where sumo bouts take place. It is a circular area 4.55 meters (14.9 feet) in diameter, defined by partially buried rice-straw bales (tawara) set into a platform of compacted clay approximately 34-60 cm high.
The clay surface is covered with a thin layer of sand, which helps judges determine whether a wrestler's foot has crossed the edge. Marks in the sand can provide evidence in a close finish. Two white lines (shikiri-sen) in the center mark the starting positions.
Before each tournament, the dohyo is built fresh in a sacred ceremony called dohyo-matsuri, led by a senior gyoji (referee). The ritual involves burying salt, dried squid, chestnuts, kelp, rice, and other offerings in the center of the ring to purify it and pray for the safety of the wrestlers.
Because the platform is raised, wrestlers who leave the ring can fall to the floor below. The ringside shimpan and spectators sit close to that landing area and may need to move quickly.