Disney's Imagineers are constantly dreaming up concepts for new attractions. Naturally, many of these will never see the light of day, for practical or budgetary reasons. For every new ride that does eventually get built, dozens of alternative suggestions are dropped. Some of those dropped attractions are pretty unremarkable, or variations on attractions that didactually go ahead. But some of the others are truly off-the-wall - so inventive and insane that we can't help but wish that they had actually been constructed. Here are 10 great examples of Imagineering concepts that would have been very different to anything Disney has actually built to date!

10. The Gyroball PeopleMover

Some of the most memorable scenes in Pixar's The Incredibles involve the spherical forcefields that the family's daughter, Violet, is able to generate. These can be pushed and rolled along, in much the same style as the Atlaspheres that used to features in the Gladiators TV shows. Could they have been inspiration for this mythical Disneyland attraction? According to those familiar with the plans, the Gyroball PeopleMover was to replace the defunct Rocket Rods at Disneyland, which closed just two-and-a-half years after taking over the former PeopleMover circuit above Tomorrowland. The fast-paced Rocket Rods were simply not reliable enough, and the attempt to bolt the new attraction onto the existing PeopleMover infrastructure proved to be catastrophic.

The PeopleMover/Rocket Rods track still stands empty, but the proposed gyroball-based replacement (put forward several years ago) would have seen riders being enclosed in a transparent sphere-shaped vehicle, which would have turned and flipped them around as it travelled along the track. It sounds like a recipe for motion sickness - but it's just crazy enough that it might have worked.

9. The Airplane! airport

Back in the early 1990s, Disney-MGM Studios was facing criticism from the press and some visitors. The park had debuted in 1989 to huge crowds, but only offered a handful of attractions. This was by design - Disney CEO Michael Eisner had deliberately opted to make it a "half-day park", keeping the cost low but still encouraging Walt Disney World guests to stay for an extra day. By 1991, rival Universal Studios Florida was firing on all cylinders after its disastrous debut a year earlier. Attendance at the park would eventually surpass that at Disney-MGM Studios, and Disney put into place rapid expansion plans. This included the addition of a Muppets-themed area and several smaller attractions. But Disney was also looking for a major, headline attraction. One of the first ideas to be considered was an enormous recreation of the airport seen in 1980s smash-hit disaster movie spoof Airplane. Little is known about this truly unusual concept, but it was eventually dropped when the projected costs spiralled out of control. Instead, the Twilight Zone Tower of Terror was eventually installed.

8. The Shark Dive

Following the success of Walt Disney World, Disney was keen to transform Disneyland into a similar multi-day destination resort. The problem, though, was land – it didn’t have much of it to work with close to Disneyland. Instead, it proposed building a new theme park in Long Beach, which it dubbed DisneySea and announced in 1991. It was to be the most ambitious Disney theme park ever, sprawling across 225 acres. Similar to a SeaWorld park (but with much heavier theming), DisneySea would have combined live animal exhibits with high-tech theme park attractions. It was to feature lands themed around a Grecian village, an Asian water market and a Caribbean lagoon. Each was to be themed around a real or fictional port.

Perhaps the most bizarre attraction, though, would have been located in the Adventure Reef area. This would have seen guests lowered in a steel cage into a tank full of live sharks. And we're not talking about sharks of the tiny variety such as those seen in Shark Reefat Disney's Typhoon Lagoon - but instead the full-sized, man-eating variety.

7. The Space-Age Castle

Legendary Imagineer Tim Delaney played a huge role in creating the stunning, steampunk-themed Discoveyland at Disneyland Paris. He also put forward an intriguing idea. At most Magic Kingdom-style Disney parks, there's a fairytale castle at their heart, which doubles as the entrance to Fantasyland. What if Disneyland Paris broke the mould, instead making the castle a part of Discoveryland and giving it a unique, space-age look? Of course, Disney's marketing department was never likely to allow this plan to go ahead. But we still have the impressive artwork above to allow us to imagine what might have been.

6. Stephen King's Tower of Terror

OK, let's be upfront about this. There's very little we'd change about the amazing Twilight Zone Tower of Terror at Disney's Hollywood Studios. But we do think that one of the early ideas for the ride could be revisited in the form of a temporary Halloween makeover. What was it? A version of the ride based on the works of horror author Stephen King, which could have included the likes of the creepy Pennywise the Dancing Clown from It, or perhaps a recreation of the Overlook Hotel from The Shining. In the end, The Twilight Zone was seen as offering a broader range of elements that could be incorporated into a ride. It was not the last time that King's works would be overlooked by a major theme park player - Universal Orlando also once developed a plan for a ride based on his novels.