and there is no boat taxi to take you from the airport to Enriquillo Lake, lol.
in case you rent a car, usually you get best rates booking that online back home, make sure you get it with a real full coverage and a GPS WORKING and mounted. make also sure you have exact correct directions/address for the place where you go in/near/around Enriquillo/somewhere in Barahona. it is a wide area, not civilization's central, easy to get lost driving around clueless and waste hours on such, specially when crossing Santo Domingo on the way over there. your flight arrives 1:30PM, you will seat in your rental car by 3PM, a 4hrs straight drive ahead of you, it starts to get dark very quick at 6PM. in case you get lost on the way, after 6PM you will stay lost til after sunrise. without local knowledge even with a GPS it can be a nice adventure searching the right way from Dusk til Dawn.
welcome to DR1 and the nuthouse
Mike