Whether you get a cheap pair or splurge on some Oakley M-frames (#freespeed), sunglasses are a worthwhile investment. A great reason to get a cheap pair of sunglasses is so that if they got knocked into the water, it’s not like you just lost a few hundred dollars.
One thing that I’ve seen a lot people, particularly coxswains, wear with their glasses are Chums or Croakies. Croakies actually have little floater things you can attach to your glasses too so that if you do somehow manage to drop them in the water, they’ll at least float until you (or your coxswain) can grab them. If you splurged on a pair of glasses that can make the extra $10 (or less, most of the time) worth it.
Regardless of what glasses you decide to get, two features you’ll want to look for are polarized and hydrophobic lenses. Polarization protects your eyes from the sun’s glare (which we all know can be downright killer on the water) and the hydrophobic feature allows water to bead up and slide off the lens instead of just sitting there and blurring your vision.
For regular rowers, I’d say these are great extras but not necessarily “must-haves” unless you really want them. For scullers and coxswains, who heavily rely on being able to see what’s in front or behind them, definitely look into getting a pair of shades that have those features. Pro tip, your steering will be a lot more effective if you can actually see where you’re going.