With UPRM  one of the larger campus of the UPR system, the student population makes up a large proportion of the nightlife Monday through Thursday. There are several bars on Calle Post close to university that are popular among students. Locals frequent La Tertulia-bar or Oyster bar mostly on Fridays and Saturdays, you will find a mix crowd from early 20 to late 30s. Also in town: Bonsai (Japanese Restaurant), La Hacienda (Steak & Pizza), La Vid (Wine & Dine), Cocktails (what's the new name?), and last-not-least La Cava del Mucaro (Wine Bar).  For adult couples and "singles of any age" looking for companions, try the dance terrace of Holiday Inn Hotel which is a nice place to dance with locals and meet ladies (see note below).   If you don't mind driving: most of the west coast is within 45min-1hr. The Joyuda area at Cabo Rojo  has a lot of seafood restaurants where you can either drink or have a decent dinner (mostly couples and families). For the young crowd, try Rincon's suffer bars such as that near to the lighthouse, El Tambu, Sunset, and JD's in Aguadilla. If you are fluent in Spanish Aguada's pubs such as Bungalow & Riverside Castle are a good bet. (Rincon, Cabo Rojo, Aguadilla and Aguada are neighbor towns located relative close to Mayaguez, at least for the locals who are  desperate for action). Boqueron is frequented by locals and tourists alike.

Note for the gentlemen of any age:  If you want to impress the ladies at night wear an ironed long sleeve shirt and leather type shoes.  No sandals please! As anywhere in the world, men are judged by their shoes.  You can wear any type of pants as long as they are not short.  Locals usually wear jeans especially dark jeans at night.  It may sound strange to you but t-shirt underwear is a turn off for most of the chicks. It really doesn’t matter how hairy you are. Finally, a cool water type cologne is a must. Good luck and have fun!