Honolulu is a fairly safe city -- some call it the safest large city in the U.S. As a huge tourist destination, Honolulu manages to stay friendly, helpful and largely safe thanks to a decent economy and, perhaps, the Aloha spirit.

The usual precautions are in order: Don't leave valuables unattended, especially not in your car. Lock your doors, and be aware of your surroundings.

Generally, much of Honolulu caters to tourists (and members of the military), so Waikiki and the surrounding areas are safe. Downtown and Chinatown are heavily populated by homeless during the evenings, though they are generally quite friendly. Pedestrians and other drivers, particularly tourists unfamiliar with local roadways, do not always act "properly," so be extra careful if driving.

A general recommendation for any unfamiliar area, including Waikiki: Avoid traveling or walking alone at night. If staying with a group is not an option, make sure to remain in lighted areas and take safe modes of transportation (car or taxi). 

Most people visit Waikiki at least partially for the water activities, and there are certain inherent dangers that go along with spending time in the water. Swim in designated areas only. Check out the Oahu Beach Directory for a list of life guarded areas around the island. There are strong undertows, rip currents and other hazards on many of the area’s beaches. Visit Hazards for a list of dangers, including how to avoid most of these situations. Visit the American Red Cross web site for a list of general water safety tips. For all emergency situations, dial 911 from any phone.             

If you plan on hiking, you can rest a little more at ease than most other places. Hawaii is almost empty of snakes (no true native species), and no poison ivy or oak has infested the trails. Many other insect pests are also far more manageable than you might expect. Some ponds and lakes, though, may not be safe to drink from as certain bacteria can be quite harmful. Also, jellyfish have a habit of showing up on local beaches, but only about once a month, and it is always well publicized (signs, lifeguards, newspapers, radio all will mention it).

Finally, on a very different note of safety, make sure you wear your sunscreen! 

It's a fantastic city, Honolulu!