I have a less well known gps receiver by Lowrance Electronics, the Globalmap 100. Its built in mapping included coastal, river and lakes with pretty good precision. Nav aids info is available with optional software. I find it maintains lock better than my son's new E-Trex vista in heavy cover. It's an older unit without WAAS or compass however. They have a new unit due out soon called an "iFinder" . I like the buttons for menu selection and control better than the E-Trex wobble stick.
Also the Lowrance has very good water proof rating compared to most other units and can be submerged for short times. check it out at lowrance.com