I don't recommend poltpropylene jumpsuits, for a lot of reasons. They are bulky, tend to stiffen, are not that flexible, and in general are the worst of both worlds.. They are close to worthless.
Real skins are strechable spandex, providing no temperature protection, but protecting from jellyfish and other stingers, sunburn, and minor scrapes. Get a good one. They have zero boyancy and can be folded almost to pocket size.
1mm neoprene, microprene, etc, provide more protection from everything, plus a little warmth. They take up more room, but are very useful in warm water, and have very little bouyancy. I use both skins (only lycra /nylon suits are really skins, correctly speaking), and ultrathin neoprene in the tropics, and even here in the North East when temps in shallow water get up near 80F. Skins are also as slick as silk, and make putting on a neoprene dive suit of any thickness extremely easy when they are used as the first layer.
Good skins run about $40 to $50, less on sale. One half to 1 mm neoprene ultra thin sells for about $80 to $120, but prices vary widely based on manufacturer, sales, etc.
Skins are very flexible, but any thickness of neoprene has to be a good fit. A 3x lycra skin will fit almost anybody, however large. Scubapro makes ultra thin neoprene in a wide range of sizes.
