Don't be deceived by the crowds on the Kuta or Legian beach areas. Even though the beach here is quite dangerous, you still see people swimming exactly where they are not supposed to swim. It is common during the busy July and August period that as many as five people die or turn up missing over a six week period. During this same period, another four or five are pulled out of the dangerous undercurrents in front ot Surya Restaurant and the Padma Hotel in Legian.
If you extrapolate this over the course of a year, you get 40 fatalities a year due to drownings off Kuta and Legian.
There are certain facts that all tourists should be aware of when they arrive at Kuta. First, there are extremely strong undercurrents. Second, because Indonesia still does not have the resources that Australia, the USA, or Japan, if you get pulled out to sea, well, it's basically you and the ocean, and if you are not Mark Spitz, the ocean will win. Between Kuta and Legian, there are only four lifeguards (beach security is trying to increase that number). Kuta is also not blessed with access to speedboats or helicopters that will come fish you out it you are unlucky enough to get pulled out to sea when the lifeguard is not looking your way.
Moreover, once it gets dark, there is no way that anyone can find you out in the endless black ocean. Indonesian authorities simply do not have access to the strong strobe lights necessary to conduct a search after dark. Furthermore, because the undercurrent is so strong, you could find yourself hundreds of meters out to sea before anyone even notices that you are missing.
Aerial searches are not conducted and the few rubber boats on hand are no match for mother nature which certainly, as the search is going on, will be pulling you farther and farther out to sea. Kuta and Legian beach is not an episode out of Baywatch where being pulled out to sea is rewarded by mouth to mouth with Pamela Anderson.
While there are dangerous areas of the beach (especially between Surya Restaurant and the bungee jump), swimming on Kuta Beach does not have to be life threatening. The beach patrol, which puts up danger signs, knows what it's doing and swimmers who swim between the safe red and yellow flags have very little chance of encountering bad currents. People only die because they swim precisely where they are not supposed to swim.