80 centimeters!
A beach ball is an inflatable ball for playing at the beach and in the pool. The one in the explorer is 80 centimeters (31 inches) across, a large beach ball. Its size is its diameter, the distance straight across the ball through its center.
Beach balls are sold as toys, and they come in many sizes. Intex, a maker of inflatable pools and toys, sells beach balls 20 inches (51 centimeters) and 24 inches (61 centimeters) across. Its "jumbo" beach ball is 42 inches (107 centimeters) across and made of vinyl, a kind of plastic. The explorer's 80-centimeter ball falls between the two largest of these sizes.
As of 2026, the largest inflatable beach ball on record is 19.97 meters (65 feet 6 inches) across, according to Guinness World Records. It was made for the movie Baywatch and shown on a barge on the River Thames in London on May 31, 2017. It is about 25 times as wide as the explorer's beach ball.
On October 17, 2009, a beach ball decided an English Premier League match. A Liverpool fan knocked the ball onto the field at Sunderland. A shot by Sunderland's Darren Bent hit the beach ball, changed direction and went past the Liverpool goalkeeper into the net. The referee allowed the goal, and Sunderland won 1–0.
The BBC noted that the Laws of the Game suggested a dropped ball instead, in which the referee stops play and drops the ball to restart it. Under today's Laws, the referee must do this when an extra ball or other object on the field interferes with play. There is an exception for a ball already going into the goal, as long as the object does not stop a defender from playing it and did not come from the attacking team.