St Thomas is much safer then say Jamaican or the Bahama's. Most area's are very safe in the light of day. However, Toursits are advised to avoid the poor area's after nightfall, especially those several blocks back up from the waterfront. Places like the Waterfront Harbor and MAIN STREET are all very very safe, but venturing back into the alleyways, two or three blocks back is not advised. I have a saying--"probably nothing is going to happen to you in St Thomas...but if something did...the backstreets are where it would occur." Just like any other big city. St John by the way has virtually NO CRIME and St Thomas has very minimal crime, which is usually confined to inner island and the backstreet poor area's. The police are very friendly and very helpful to tourists on this island but are rarely needed.
I would advise not driving on St. Thomas. Traffic is heavy, the roads are narrow and winding and they drive on the left-hand side of the road. We saw so many tourists in rental cars driving like crazy and adding to the congestion. Cabs are readily available and all have standardized rates so you can't get ripped off-- just make sure you look for AUTHORIZED cabs. Driving on St. John is a little better because there are less people.
Crime is bad in certain parts of St. Thomas, particularly in parts of Charlotte Amalie so check your travel guide for tips. There are definitely places where you shouldn't go after dark.
Certain areas on St. Thomas, like most places, can be dangerous to your wallet or health. Violent crime is fairly common on this small ilsand. Most of the crime centers around drugs, so tourists are not at risk here, but some criminals prey on tourists. Downtown, especially Savan, is to be avoided at all costs at night. Some hotes/timeshares have a reputation for robberies, i.e. Beachcomber Hotel, Blackbeard's Castle. Your best bet is to stay at the larger hotels such as The Ritz-Carlton, Wyndham Hotel, or the Marriott Hotel. I have never heard of any problems at those three hotels.
St Thomas is a beautiful island and i am not trying to discourage anyone from coming here. As long as everyone is aware of their surroundings, the trip will be memorable for all the right reasons.
Iguana's are our versions of Racoons. They may look cool and neat, but they can mess you up if you scare them enough. Iguana's won't attack, but they will defend themselves if threatened. AND if you have food, they may approach you. The key to an iguana is his tail. If one hits you with it and gets a good shot in, you might need stitches. If you see one with his tail flexed and up, get away from him slowly and don't make any sudden moves. Other then that, they are fun to watch. But keep your distance, at least arms (and tails) length away from them. They can be unpredictable.
In regards to back street, SAVAN (which is several blocks up from waterfront) here's a 2005 update. Local businesses are starting to take back the area's in the back streets behind waterfront. CUZZINS, KOPAPELLI CAFE, TOMMY'S BAR and the shops on MAIN STREET (1 block up from waterfront) are all safe to go visit in the daytime. These are great places. Just don't venture anywhere further then these places. Especially alone....and especially alone and at night.
Undersea reefs are very delicate. Don't step on them under any circumstances. You'll kill the enviornment. Really. It takes SEVERAL HUNDRED YEARS for a coral reef to mend itself from ONE HUMAN STEP. It doesn't matter if you have shoes, aqua socks or are barefoot. Any contact is deadly to a reef. Stay on the sandy stuff when you are in the water. If you think you are standing on rock out there, think again...it's probably reef.
St Thomas is a fine island, and Charlotte Amalie not a bad town. Unfortunately a line of cruise ships disgorges its passengers day after day, so you have to share it with many others.