Productive fishing spots are defined by estuarine structure. The main channel, especially where it bends or constricts, creates current flows that attract predators. The edges of sand and mud flats, particularly where they drop off into deeper water, are prime ambush points. The confluence of any smaller tributaries with the main estuary channel can be productive. Areas with submerged structure, fallen trees, or oyster beds provide cover for bait and hunting grounds for gamefish. The area near the estuary mouth can be excellent when accessible and safe, but it is subject to strong currents and wave action.