As said above, consider one of the binocular harnesses designed to hold binos close to the chest. You'll want one of the more substantial designs like those from Hornady, Badlands, or such, rather than the simple elastic kind commonly available for around $20. Thise are great, but tend to sag, and if you're wading, sagging isn't an acceptable risk. Here's a link to one option:
BINO BASICS - Optics - GEAR
Youd want to make sure you could cinch it up tight enough not to bounce to water level, but also where you could still pull it up to eye level, also. Might be worth a call to Badlands. They're a great company with sterling customer service and warranty. I'm a decade deep into using one of their daypacks, and it's been pretty hard used, and still looks almost brand new.