Two Fathers 4 Justice campaigners were arrested after spending two-and-a-half-hours at the top of a Blackpool Pleasure Beach rollercoaster.
Rides had to be shut down for the duration of the protest
The Pepsi Max Big One was closed after the men, dressed as cartoon characters Batman and The Incredible Hulk, got on top of the ride just before midday.
Rory Wilmer and Colin Wallace, both from Liverpool, climbed a stairway at the side of the 235ft (72m) high ride.
They were bailed until 12 November for further inquiries to take place.
Members of Fathers 4 Justice have previously scaled Buckingham Palace and the London Eye.
The men said they were protesting because they were unable to take their children to the funfair.
The stunt cost the Pleasure beach tens of thousands of pounds
Mr Wilmer said it was his son's birthday next week and he would not be able to spend time with him.
"I won't be able to see him on his fifth birthday, so I've climbed on top of this ride to tell him that I love him," he said.
The pair came down at about 1430 BST and were arrested.
A spokeswoman for the Pleasure Beach said the park had lost tens of thousands of pounds due to the stunt, as the ride usually takes 1,200 people each hour, at a cost of £7 each.