The annual Worthing International Birdman competition was halted for around 20 minutes after a competitor injured herself and had to be rescued by the lifeboat.
The woman, named by organisers as CBBC presenter Holly Walsh, was strapped to a spinal board after being rescued from the water by divers and was taken to hospital with a suspected dislocated shoulder and fractured arm.
Around 10,000 spectators were believed to have attended the second day of the two-day event, where so-called "fun flyers" dress up in elaborate costumes and attempt to "fly" the furthest off the West Sussex town's pier.
Entrants included a pair dressed up as the Owl and the Pussycat complete with rowing boat, and Batman and Robin.
Before launching herself off the pier, Sam Hallett, 44, from Shoreham, who was dressed as Penelope Pitstop, said: "It's my first time. I'm a bit nervous. I've just been told to go feet first and keep straight."
Elaine Sinclair, 51, from Worthing, said it was the second time she had taken part in the event.
She said: "The one thing I've learnt is to wear shoes, as it wasn't much fun hobbling up the beach afterwards without them last time. The main thing is to not take it too seriously and to have fun."
On Saturday, Eddie the Eagle took part in the more seriously-taken competition, where entrants launch themselves off the pier in gliders and other makeshift flying contraptions. The one-time Olympic ski jumper, who flew complete with skis and ski poles, only managed to fly 7.52m before ending up in the sea.
Speaking of the injured woman, Shoreham lifeboat spokesman Dave Cassan, said: "We can confirm we were tasked to get a person out of the water.
"It appears she entered the water wrong. It is thought she has a serious fracture above her elbow and a dislocated shoulder. The inshore lifeboat brought her to the shore at Worthing and she was transferred to hospital by ambulance."