As the name suggests your objective will be to hunt down as many beach goers as you can. At the top of your screen is a kill count that you need to reach.
You can eat both the people swimming and the people on boats. When they fall into the water you can attack them. Aside from that you can get a speed boosts for a while.
You also need to take care to look at your time, since a longer period of not killing anyone could mean game over. Will you be able to get through all of the levels on your first try?