The Gulf of San Miguel, 30 km wide at its mouth and extending 40 km inland, is the estuary of river systems that drain eastern Panama. The Gulf consists of a central scour channel up to 36 m deep, flanked by semicircular bays. The tide has a range of up to 7 m, and maximum surface tidal currents average 200 cm/sec on the flood tide and 230 cm/sec on the ebb tide....