Ocean Waves is an application that simulates the sound of waves on your Mac. After starting the sound effect, you will be able to listen to the waves indefinitely, without changing any settings. The sound of the waves is realistic enough for me and one of the things that I like about it is that it never seems to repeat. Also, at times, the waves sound louder on the right speaker, and, at other times, they do on the left one, which makes you think you are standing on a long beach.
In the Preferences window, you can change settings for the Sound Generator and you can also enable the Amplitude Generator. These basically determine how the waves will sound. I didn't really touch any settings because the default ones worked just fine for me.
Ocean Waves is, in my opinion, better than simply listening to one of those nature MP3 which go on a loop every 2 or 3 minutes. The sound quality isn't as good, but Ocean Waves can be customized and it seems like no two waves sound the same.
If you want you can export the sound to an AIFF file to play it on other devices.