Kenwood's KMR-D362BT, Sony's DXS-M50BT, and Dual's AM75BT are among the marine stereo/speaker packages that are highest rated at West Marine, as of 2015. Other well-regarded marine stereo systems include Poly Planar's MR45D and West Marine's WM7000.
Sony's DXS-M50BT features marine-coated circuit boards that are designed to withstand aquatic conditions. Dual's AM75BT also utilizes coated circuit boards in addition to an EDP-coated chassis that is rust resistant and a UV-resistant faceplate that can be detached to prevent theft. Look for UV and water resistance, a high-powered amplifier and multiple sets of preamp outputs (for upgrading to a larger system later) when shopping for a marine stereo system, recommends Crutchfield.