How near is "near?"
I've killed 2 deer this year that were bedded within a few yards of a creek or river. Running a boat up to a couple hundred yards of the spot and then running the trolling motor up to a spot on a trail just outside the thick cover payed off. One deer got killed on the first sit, and the other got killed on the 2nd sit because I passed him on the first sit.
In general, deer do not expect danger from the water. I've watched them casually observe bass fishermen pitching the banks several times without showing any signs of alarm. If you can approach quietly from the water, it's perfect access. No ground scent, reduced sound profile, and generally in a small boat you're low enough in the water that the bank hides you until you pop up at your spot.
If that's not possible and it's as thick as you describe, the only option I see is getting as close as possible on an exit trail. Some of the stuff I've seen deer bed in isn't something you can penetrate without the kind of prep work that is generally frowned upon on public land.