Just a technical note: Flexibility, like everything else about the body, tends to be specific. As people have already mentioned, some skaters have very flexible backs, some hips, some are extremely flexible is several areas. Also don't forget, we usually only see what the skater does well. For example, people have asked why Irina gets so little amplitude on her arabesque spiral when obviously she has great hip and back flexibility as demonstrated on her Biellmann spins? For one thing, to do a 180-degree arabesque spiral a la Sasha or Nicole Bobek not only takes flexibility but also strength in the hip and back to hold the leg up. With Irina, by combining the great flexibilty in her back with good hamstring stretch in the hip, she gets a good Biellmann position. But she just wasn't built with the hip structure and perhaps just never worked on getting the strength to get more amplitude on the free leg in her arabesque spiral. Even Lucinda Ruh, who has great flexibility in a number of positions, has an arabesque spiral that only gets to about 130-140 degrees (it's still a beauty though--great speed, long legs, great extension). It's probable that even superflexible skaters such as Natalia Mishkutenok, Utako Wakamatsu, and (Don't Know Her First Name) Leonova can't do a 180-degree arabesque spiral the way Nicole Bobek or Sasha can. But then there are probably things Mishkutenok, Wakamatsu, and Leonova can do that Sasha and Nicole can't. Same goes for other skaters mentioned, such as Ruh, Krieg, Ota, Nam, etc.
The only people about whom you could say they have overall extreme flexibility are contortionists and even they have to work on a lot of things and sometimes cannot do certain moves that require both great strength and flexibility. It's not that they're lazy, it's the way their muscles are constructed, ie, very long muscle fibers that make it difficult to gain and retain strength. To see a very flexible skater who also exhibits good strength moves is especially impressive to me.
Most flexible skater I've ever seen: Without a doubt, Piel. She could lay back so far on her layback she'd end up looking at the audience from the level of her belly button. Her spiral had so much amplitude, they stopped measuring in degrees and just talked about how many times she "wound the clock." In her Russian split jumps, her legs went all the way up the sides of her body and crossed in back of her head. In fact, one of Piel's moves was banned for being too Kama Sutraesque. You just don't see that kind of flexibility on the ice anymore
Rgirl
but I wanted to correct:
