Is a long wetsuit a suitable choice for swimming in the sea and not surfing?

it all depends on the temperature of the sea and how big the drop is between winter and summer. Also some suits are far better than others and keep you alot warmer because of the quality and how further up the technical scale they are. Obviously the more money you spend the better suit your going to get, but i would advise getting something like an O'neill Psycho or a rip curl f-bomb. these are both excellent suits, and they also have thickher and thinner versions for if your in cold or warm waters. ask your local surf shop what thickness suit to get, and if they dont know, just get a 5mm. you can't really lose with that :) hope this helps