Don't waste money on junk. I use a pair of Leopold from Cabela's for everything outdoors. Once you have a good pair, you take 'em every where. A crummy pair will give you a headache with the parallax that they can produce. Don't get anything stronger than an 8X because you can't hold them still enough standing on dry land, let alone bobbing on the water. Get at least a 42mm lens to gather good light, have a BIG picture and less eye strain.
One thing about Leopold; they have a lifetime warranty. I had a 3 year old set that started leaking first week of duck season. I called them, mailed back and they sent me a new pair within 2 days. Then they fixed mine and sent them back too. Yes, they are that good.
Get a roof prism because they are compact and light. A porro prism is heavier but less expensive if you want to compromise weight for price.
You won't be sorry getting a good quality pair and be sure to read user reviews.