Hawaii is generally a safe tourist destination, but it's still wise to follow common-sense safety precautions. Hotel and visitor-center staff can provide information should you decide to head out on your own to more remote areas. Don't leave any valuables in your rental car, not even in a locked trunk. Avoid poorly lighted areas, beach parks, and isolated areas after dark as a precaution.
When hiking, stay on marked trails, no matter how alluring the temptation might be to stray. Weather conditions can cause landscapes to become muddy, slippery, and tenuous, so staying on marked trails will lessen the possibility of a fall or getting lost. Be sure to heed flash flood watches or warnings. Never try to cross a stream, either on food or in a vehicle, during these weather conditions.
Ocean safety is of the utmost importance when visiting an island destination. Don't swim alone, and follow the international signage posted at beaches that alerts swimmers to strong currents, man-of-war jellyfish, sharp coral, high surf, sharks, and dangerous shore breaks. At coastal lookouts along cliff tops, heed the signs indicating that waves can climb over the ledges. Check with lifeguards at each beach for current conditions, and if the red flags are up, indicating swimming and surfing are not allowed, don't go in. Waters that look calm on the surface can harbor strong currents and undertows.