Not a problem. I am a single woman and made the trip down to San Pedro alone. Spent 5 days there before I was joined by some other friends. Even walked downtown for dinner and back to my accomodations after dark. No one bothered me at all. Of course, I did have my wits about me and I am a US Marine. So perhaps I projected a "don't even try it" attitude. I really think you will find San Pedro safe and relaxing. The local people are friendly and very helpful.
I assume you like to dive as well. Let me recommend a little family run dive operation that I used the whole time I was there. Did 11 tanks with them.
I went with Coral Beach Dive Shop which is on the pier next to Shark Bar. First, let me tell you about an overnighter to the outer cayes and atolls. The 50 ft boat we went out on has bunk beds and was a very cool experience. The boat Offshore Express II is actually the boat used in the filming of Cocoon.
We dove 3 tanks the first day at Turneffe, Long Caye, and Half Moon Caye. Stayed overnight moored up at Half Moon Caye which was like a private tropical paradise. The next morning we headed to Blue Hole and had already surfaced by the time the first boat from AC (Amigos Del Mar)had arrived. We headed for Turneffe for our last dive and then back to AC.
The crew was a family operation. Alan Forman is a PADI Platinum Dive Instructor and has personally trained his dive masters. His son Clive captains the boat and is a dive master. Drury, another son, catchs fish along the way and assists as a crew member. Norma & Dalcia are two daughters that manage all of the cooking and bedding and all of the guests on the boat comfortable.
The trip cost us $250 US for the dives, all meals, and accommodations. We left Tuesday at about 0630 and were back well rested with a siesta on the return trip by 1630 on Wednesday. The food served was plentiful and excellent.
Here is a website that goes into a little detail on the trip. http://www.coralbeachhotel.com/
Alan doesn't own this hotel anymore, but does have the dive shop going. I highly recommend this dive shop for local diving as well. Alan Jr., the grandson, who runs one of their other boats Offshore Princess is an excellent dive master for local checkout dives.