OMER 6, a one-person submarine, achieved a speed of 4.916 knots (5.65 miles per hour), beating the previous 4.642-knot (5.34-mile-per-hour) speed record for subs without a propeller. The two-person OMER 7 sub hit a top speed of 5.133 knots (5.90 miles per hour).
Students imitate penguins to set people-powered sub records By Larry Greenemeier in 60-Second Science Blog (Scienfitic American)