The pontiff has given his backing to a project by his advisor Monsignor Konrad Krajewski.
The polish priest, who oversees the Vatican's work with the poor, takes a van of ten people to a nearby beach for the day and stops off at a pizzeria on the way back.
The Vatican supplies the swimsuits and beach towels.
Msgr Krajewski said the afternoon outings had been set up to meet the "desire for normality" for those living on the streets near the Vatican.
In recent months Vatican officials have opened showers and barbers near St Peter's Square for the homeless as well as increasing the number of hot meals they give out.