I’ve been testing Costa’s polarized Spearo sunglasses, a suave tortoiseshell frame set with green mirror polarized glass lenses, and I’m head over heels. After a couple of road trips, a handful of hikes and 20-plus days on the river, these casual adventure shades have become my all-time favorites.

The fit, style and optics have combined to win my affection. The castor oil-derivative bio-resin frames (points for sustainability!) are slightly oversized. And the easygoing style is underlined by a notched nose bridge and sculpted logo-embossed arms. The fit is true medium. Grippy nose pads and inner arms have kept these shades secure on the sweatiest of hikes. Each temple is perforated with a tiny hole, so you can attach Croakies and save the Spearo’s from being sacrificed to the river gods. And on a recent father-son fishing trip, my Costas were the hero we needed to save us from an empty line.

A trout darts to the surface of the cerulean creek — a tiny brown torpedo materializing from nowhere. The fish wallops my dad’s dry fly, and upon discerning duplicity, instantly spits it out and disappears. I let out an inarticulate, garbled groan, equal parts excitement and despair. Thinking my constipated caveman yodel a signal to strike, my dad yanks the rod a second too late, slingshotting a fishless fly into the air.

“When you see a fish take the fly, you’ve got to set the hook,” I tell him for the third time, heart pounding at the near miss. “Immediately. They’re quick and I can’t yell fast enough.”

“I just can’t see the fly,” confesses my father, shrugging sheepishly. It’s his first day of fly fishing, and he’s doing remarkably well. He hasn’t caught a fish yet, but he hasn’t lost a fly to the overhanging tree branches, either. After a quick lesson, he’s getting the hang of it. The fish are biting, at least. He just can’t see them.

“Here,” I remove my Costa’s and hand them carefully to my dad. “The green lenses will help. But please be careful, I love these things.” I’m a fan of the glass lenses. Not only do they offer unrivaled optical quality, but they also have a welcome heft to them – in stark relief to cheap, flimsy gas station knockoffs. Available in both glass and cheaper plastic, Costa’s premium 580 lenses filter out yellow light while amplifying reds, greens and blues, all while defending against UV and High-Energy Blue Light. While I’ve not put these lenses through any lab tests to support Costa’s technical claims, both my dad and I have been thoroughly impressed with the Spearo’s optics where it counts the most: on the river.

We trade, and I put his sunglasses on and snort. His brown-lensed shades darken the scene, muddling colors, whereas the polarized green Costas add a crispness, allowing one to easily distinguish between the latte-colored foam and the tiny, feathered, beige fly drifting downstream.

Sure enough, within ten minutes, my dad hooks an eight-inch rainbow — his first-ever fish on the fly. A whoop escapes my lips. He lands the trout, grinning like a little kid, and I can’t help but feel that our roles, at least for a moment, have been reversed.

Costa provided this product for review.