Rincon Channel runs under the 181 causeway and serves as the main passage for larger vessels to get to the Rincon Point industrial area. This is the main body of water that connects the Corpus Christi Bay to the Nueces Bay and has a lot of trout fishing action due to its depth around what is mostly shallow flats. A lot of locals like to get beach chairs and stop right off the cause way for some great, quick and easy access fishing.
The main fishing pier in Portland TX is the Indian Point pier this pier is located of the causeway near Sunset Lake Park and sticks out into Corpus Christi Bay. This pier has lights and was recently renovated making it what I consider the best public pier in Portland TX. This pier has a history and legend for producing some of the largest black drum or big uglies as we like to call them during the annual drum run and you can get reports when the bite is on at Indian Point Pier on Facebook normally.
The other body of water Portland is connected to is Redfish Bay out of Aransas Pass Texas it is connect via Corpus Christi Bay and the La Quinta Channel that runs along the shoreline and takes you through Ingleside on the Bay. The La Quinta Channel gets its name because it runs along the shoreline on the west side of La Quinta Island. This island has a hard sand bottom due to the dredging that keeps the channel deep and is good for trout and flounder all year.