Portmore is a nice suburban area...I always say it's the Jamaican equivalent of Hoboken, NJ. Nothing to do, but it's pretty safe.
Unfortunately, this is a local beach in my neighborhood, and is not located in a tourist area. Unless you are going with a local that lives there, and is familiar with the area, I would not venture out to find this place. The good news is, it is just a taste of what Jamaica has to offer.