A man in his 50s was pulled from the water off Calshot, New Forest, after a collision on Sunday, 5 July.
The father, who was brought to shore, collapsed soon after the incident. The rider involved was not arrested.
Emergency services responded promptly. The injured man was taken to the nearest hospital by ambulance.
He passed away at the hospital on Monday, 6 July.
The next of kin have been notified. A file will be prepared for the coroner.
