We are always a little bit apprehensive when we approach Corinto with a ship. The port of Corinto is reached via a narrow channel about 3 miles long which leads towards the estuary of a river along which the docks are located. That shallow water poses a problem when there is swell. If a long rolling ocean swell comes in, the waves heighten when they come onto the shallow part. Waves have amplitude which is half under water and half above water, when looking at the mean height. When we see the down part of the wave it is really a hole that is normally filled with water. On very shallow depths, that hole cannot go down. It still has to as the waves roll on. So the whole wave system has to go up. As a result ocean waves rolling in over shallow coastal areas get higher until they crash on the beach. (This is the simple explanation, if I have to do it 100% correct, it will take me two pages) You have a similar phenomenon at rivers where there is a bar outside. Such as the Colombia River going to Astoria /Portland or the Garonne River leading to Bordeaux. Continue reading