Ripped... or rip off?

Here's a photo from Triathlete Magazine. Look at the guy front row, second from left. I need somebody to explain something to me: how is it possible we can see his abs through his wetsuit? This isn't a question about diet or sit-ups; this is an issue of physics and three-dimensional geometry.

Wetsuits are not spandex. Even the most high-tech materials have a significant thickness to them to provide a layer of insulation against the frigid, jellyfish-infested waters. I could shove a half-dozen bricks into my suit and the material would simply smooth out all the lumps to make it look like I was carrying an alien love-child. So what's going on with this guy that we can see such level of detail?

My current theory is that the grooves are actually just painted on to the suit, creating the illusion of being in shape. All I know is that I also have a sleeveless Xterra suit and I don't look nuttin' like that. I need to get me one of those.