In Stockholm, there's a diagonal wind tunnel used for one very specific purpose: learning to fly a wingsuit

This is kind of why I want to get into skydiving actually. Wingsuiting looks really fun, kind of a hybrid between paragliding (well, really, speedflying) and skydiving. The lifting body principles & travel of a parafoil with the speed of skydiving.

I've looked at getting my AFF completed, and it's not too expensive actually, cheaper than paragliding for sure; but the real cost is in upskilling your skydiving skills to the point where you've got your C or further license; which is decidedly less cheap.

I'm skeptical whether the costs of training on the ground using a machine like this are worth it for someone who already has a skydiving license; which you'd need as a prerequisite. The wind tunnels used for skydiving are often super-touristy and pretty expensive—I think personally the cost benefit analysis favors just jumping out of a plane for real.

Either way, freeflight is a fascinating addiction, and every discipline has its own tradeoffs of enjoyment, flight longevity, and exhilaration. One day I'll give this a go!