You can go swimming any time of the year but there is a special pleasure in swimming in sun-warmed water in the summertime. Whether you're in a pool, a lake, or the ocean, if you're going to be spending time underwater, your eyes will thank you for a good pair of swim goggles.
Competitive swimmers like swim goggles made without gaskets in them. These have less drag than other goggles. Goggle frames with gaskets use the gasket to keep water out of your eyes due to the snug fit. These are popular with people who are swimming for the sheer pleasure of it rather than in competition.
You want your goggles to be comfortable yet snug enough to keep the wet out. Try on goggles before you buy and make sure they provide a little suction to your face. If they leave red rings on your face afterward, they are too tight. Your goggles should have a good solid band that holds snug around your head. You can end up with a stretched-out band if you buy cheap goggles, which means your goggles won't stay put, and won't keep the water out.
Lenses come in a range of quality and prices. The cheaper lenses are made of plastic. Lenses that are optical grade are made of material that is also used in the manufacture of eyeglasses. The highest quality lenses provide anti-fog protection and UV protection, as well as resistance to scratching. Antifog protection, as the name suggests, keeps them from fogging up in the water. If you still end up with a little haze in there, you can put a bit of water inside your goggles and move it around to get rid of the fog effect.
If you're swimming in an outdoor pool during the day, you may want lenses that are highly tinted. If you are swimming in an indoor pool, or if you prefer to swim later in the day in the evening, clear or low-tint lenses would be a better choice. If you are more fashion-conscious and aesthetically inclined, you might be interested in matching the color of your lenses to your outfit for the day.
If you normally wear glasses, don't feel left out, corrective swim goggles are available where you buy your eyeglasses. These type of goggles are more pricey.