They glide downwards using the “wing” and ballast and use a gas bottle buoyancy device to get back to the surface; have a look at http://www.guillaumebinard.com/gallery/oceanwings/
Aqua Lung Oceanwings / The underwater human flight experience
And now, in complete contrast to the former dreamy sequence, here is the latest wing suit mayhem. Don’t get confused by the smoke – it’s not jet propulsion à la Yves (Jetman) Rossy - it’s 1) so one we can see their track better and 2) so they can see each other better as they manoeuvre in narrow spaces at very high speeds.
Dream Lines IV - Wingsuit proximity by Ludovic Woerth & Jokke Sommer