Snavie
Do not panic

!!!
I have stayed at the Playa Mar and can tell you the nearest beach is about 250 metres away but it is very narrow (only about 10/15 metres ubtil you hit the sea).
The walk along the Pine Walk to the marina/town centre is about 800-1000 metres and you can stroll it in 20 minutes no problem. It is very pleasant and pedestrianised and you can use a buggy on it athough bits are a bit bumpy due to the type of paving they have laid.
The main large beach is past the marina and probably another 400 metres or 3 minute stroll.
Any other questons feel free to ask.
Have a nice time, when are you going ?
Cheers
Dave.