I believe there was a calculation made which showed that a wave crashing into a mile of beach represents more energy than man has used since he first learned how to light a campfire. Can't find the right wording to locate it in Google.
Man I wish that were true, we could solve the energy crisis. Here is an equation to calculate wave energy:
CACR Wave Calculator
Also, this site is great for wind and wave prediction:
Sailing Weather - Marine Weather Forecasts for Sailors and Adventurers - PassageWeather
Use the animate button to make the waves move, you can see how they propagate around islands. Noice that if an island is surrounded by real deep water, the wave will not refract so much to the opposite side, if shallow water wave will refract around.
There are 3 basic types of waves, those generated far off shore from large storms that bring in a ground swell and when that hits the beach, very large waves. This happens in Hawaii when storms around Alaska generate swell. It can be a calm sunny day with no waves at the beach and within 1 hour you could have 20 foot wave faces breaking- a lot of people die this way. Then there is the local sea breeze- air heats up on land, rises, and creates a wind heading to the land which generates a wind chop. Then the tidal wave which is generated by earthquake or underwater land slide. Also you could have a local storm (low pressure area) that would generate waves, but generally it will also be stormy at the beach also (wind and or rain/couds).