A recent saturday (29th of May 2010) I was out paddling outside Höllviken with a friend. The weather was quite constant, and all photos are from the same short period spanning a couple of hours. During that time, the weather did not change, but due to the different depth of the water during the trip, the behavior of the sea changed. We shifted between calm water, calm water with a lot of foam, and water with some waves and foam (as usual, there is no photo from the higher wave paddling).
The route we travelled was tracked on my GPS. Picture to the left is from google earth. Clicking on the picture gives a hi resolution version of it, and the google earth file can be reached by following this link (you need to install google earth on your computer if you do not already have it).
We left Höllviken in strong gale, but calm sea. The reason for the calm sea was that we started on the side pretty well protected from the wind through the shore a bit away, and also since the water was extremely shallow. However, after crossing a reef and getting maybe 100 meters out from the shore, the water got a little bit deeper, and with that came some waves. Not big waves, the water was too shallow for that, but water was anyway covered by a lot of foam, created by the strong gale, which also made paddling quite heavy. The water was simply not deep enough to host big waves, although the wind was creating them where there was enough water.
After about an hour of paddling, we were on the wind protecting shore itself. Here the water was very shallow, and for a long distance. Thus the picture shows a perfect nice sunny and calm day. But in fact, it is still blowing strong gale. This is hinted at by the water being a bit rippled a distance out from shore. The depth of the water is not more than 2 decimeters, which is the reason why no waves are built.
Shortly after starting the trip back, we are reaching water that is somehwat deeper. Immediately the wind effect starts becoming visible again. Foam starts forming, although it is not deep enough for the waves to become high. Also, looking close at the water, a lot of ripples from the strong gale can be seen. This is the reason for the quickly developing waves, as well as for the streaks of foam.
The shift of the environment goes on on the way back, as it did on the trip out. The wind continue to blow steadily and strongly. When we are on waters that are deeper, we see waves. The deeper the water, the higher the waves.
As soon as the water becomes more shallow, the waves disappear again. The wind is still as strong, so we paddle in strong wind, with foam on the water, but without waves.
When finally arriving onto the beach, we again have a very idyllic photo, since the water is now extremely shallow again. It is still the very same strong gale blowing out there.