Thanks for your message. Villamartin is a vast area, so vast that I had not heard of your area but Googled it and understand it is in Blue Lagoon.
This is an area of Urbanisations each having their own Community swimming pool and some local bars, but pretty much nothing more, sorry.
I would guess even for the fittest you are looking at an hours walk (at the least) to the beach although if you can get yourselves up to the Villamartin Plaza (we live just around the corner from the Plaza) there is a bus to Torre and also to the local beach at La Zenia, in the summer months.
Sorry cannot help re the moped hire either, been here eight years and never seen it advertised anywhere, but then again being of an older generation it maybe does exist but not noticed it.
Hope you have a great time, sun and each other what more can you want
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Denise