Every wetsuit maker will advise you that after each usage, you should clean your suit with warm water and hang it inside out to dry in a cold, dry spot. They advise this mostly because salt water is bad for your suit. But it also helps if you want the feel of a new suit.
If you don't wash your suit right away, there's no need to panic. The smell will go away on its own after a few days if you don't wash it.
Saltwater can damage a wetsuit if you don't wash it after every use, especially if you swim in coastal waters. If you don't, you'll be wearing out the material faster than it should be. Even if you don't touch any salty things, the amount of salt in some waters will cause your suit to smell like a fish tank after a while. This is only natural since chlorine is used to treat swimming pools and other bodies of water so they are not recommended for washing your wetsuit.
There are two ways to wash a wetsuit: manually or in a machine. If you choose to wash it by hand, first take all the parts of the suit apart (except the hood which comes off when you wear it) and then wash each part separately in hot water with a mild detergent. Make sure that you rinse each part thoroughly before putting it back together.
After each use, rinse your swimsuit in cold tap water as soon as possible. It's much better for the fabric if you can soak the suit in cold water for 30 minutes. Most of the chemicals, salt, sand, and body oil that might harm the cloth will be removed during the soak. Pure water does not completely eliminate the salt or chlorine. But it helps "rinse out" any other chemicals that may have been applied to the suit.
If you don't have time for a full-on bath, then at least wash your hands after using the pool or beach. This will help remove some of the chemicals from the sunblock you used on those hot days by the pool.
Also, do not wear your swimsuit for more than seven days without washing it. If it gets too dirty, you'll need to take it off and wash it.
Finally, only buy one-piece swimsuits for women, they are much more comfortable to wear.
Rinse your swimsuit. A little chlorine bleach added to the water when washing your clothes also helps remove stains and odors from the suit.
Don't wash your suit in a machine. This should be done only at home with hot water and detergent. Washing machines are very harsh on fabrics, especially nylon and polyester ones used in swimwear. The heat from the machine can cause these fibers to lose their strength and break down over time.
Instead, hand-wash your suit in a gentle cycle. Make sure not to use any scents or colors when cleaning your suit because they'll just make it smell like everyone's favorite beach getaway.
Dry your suit thoroughly after washing it. You don't want to put it in the dryer again before it's completely dry. This will cause its shape to change and may even start another round of shrinking.
Finally, keep an eye out for any rips or holes in your suit. If you find one, don't wear the suit anymore. Instead, take it to a tailor to have them fix it.