The Mainsail is amazingly lightweight, and you gotta love that blue.

The polycarbonate Mainsail is one of my absolute favorite everyday, all-round sunglasses, which is saying a lot, given that Costa makes some of the best glass lenses in the business. Click here to read about the spiffy glass Hammerhead. But no glass lenses come close to the gossamer essence of Mainsail, the kind of shades you simply forget are on your face. Until you take them off, that is, and glare and wildly scattered light are restored to their cornea-stabbing norm. Mainsail may be wondrously lightweight, but its gently curved rimless nylon frame with supersoft rubberized nosepiece holds this pup firmly in place throughout any active pursuit—I gave myself whiplash trying to jettison it. Behind the spiffy blue mirrored lenses is a gray base tint that delivers a realistic world view along with just a smidgen of exterior attitude. The lenses are polarized, of course, and permit 10 percent visible light transmission—just right for long days anywhere but atop K-2. I’m already ruing the day that Mainsail acquires a scratch, but Costa’s standard hard case, lens cloth, and sunglass retainer increase the odds of Mainsail’s living a long and active life. Not Rx-able. $169 from Frames Direct. Click here for free shipping.

Click here for tips on buying the right shades for summer beachgoing.
If your beachgoing sojourns might include stints of sailfishing off Isla Mujeres, Hammerhead is for you. Costa is all-polarized, all the time, and they’ve got that act down very well. Hammerhead is a supreme tamer of glare. Especially in our test shade, featuring Costa’s premium 580 glass lenses in a soothing yet thrillingly crisp gray base tint. The “580” stands for the ability of the Rx-able multicoated glass to block annoying yellow light around the 580-nanometer wavelength. Not that you’d know it per se, but you do know that colors appear saturated and the eye just plain feels good looking through. The shiny wrapped 8-base frame has beefy temples for side protection and spring hinges for rough-stuff durability. I could wish for an adjustable nosepiece or at least some nonslip features, but I couldn’t wish for better glass. $149 from Frames Direct: Click here for free shipping.