We had to overnight one night in San Andres (coming from Providencia which is much quieter).
We had booked on Expedia, where the address of the hostal is technically correct, the problem though is that nobody refers to houses with a street and house number, rather with references to other hotels or buildings. This meant for us a 1 1/2 walk with heavy luggage through the town, asking about 25 different persons and nobody could direct us to the correct hostal. As it is relatively new taxi drivers and other hostals don't know Mar y Mar yet....
Second problem was that the way the phone number was written on the Expedia confirmation it looked like a wrong number to the locals (as the regional code is different and the number of digits didn't seem correct)...finally we found a nice local who figured out it was a cell phone number and called, so the owner, Javier Arias, picked us up. Should you ever find a taxi driver or the address, also take into account that there is no reference outside the hostal of its name, it basically is a private home, no sign whatsoever that it would be a hostal.
In any case, the correct reference to find it is "Diagonal Maryland". It is also very close to the Fisherman's Place, the fish restaurant of the local fishing cooperative.
Once there, we were surprised how new and modern everything was. There is currently 4 rooms, clean, with flatscreen, fridge, microwave.
We did not have hot water, but also didn't really need it.
There is no wifi yet, but Javier offered us to use their home wifi on the terrace. He also can pick you up at the airport for a fee of 12.000 COP.
As the hostal is right next to the airport there is definitely noise of planes (there is about 6 flights during the late night/early morning hours).
Other than that and our problems to find it, definitely a good option to stay.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.