How to choose a GPS navigator for fishing on a reservoir?

Garmin's eTrex series or tools like Navitel on your smartphone - both options work, it comes down to whether you're willing to spend money on a dedicated device. Waterproofing is definitely necessary if you're fishing from a boat or near water where your gadget could get wet - it's not overkill. Battery life matters too: GPS drains power pretty fast, so look for models with at least a day's worth of battery, otherwise you'll be stuck tethered to a charger. I often take a GPS unit out to my dacha and I've learned that a reliable device saves you way more time than what you spend on it.