Returned from an offshore trip and arrived at the mouth around 7:00 on Saturday. Two boats were grounded at the mouth. It looked to be around 1 to 2 feet across the whole mouth. Watched the stranded boaters wade across the mouth looking for an opening. It was an abnormal low tide. We ran to Port O'Conner and got inside the mouth around dark. We worked our way through the bay following the channel markers (green blinking lights). Once we hit the intercoastal, we could not stay in the channel and keep running aground. There was no moon to aid us.1 flashlight was of no help. We had to play chicken with two barges and follow them all the way in to the locks. Due to the intercostal being some what low the barges kept getting semi-stuck on the turns and we feed the mesquites well while waiting for them to get up to full (5 miles an hour)speed. Arrived back at he harbor around 2;00. Beware of low tides and a SCREWED UP opening to the gulf.