How bad is the sea?

Depends on your budget, front line, slightly inland many options available

Don't take so much notice of the Blue Flag status, I don't like the beach anyway but I have been on Blue Flag beaches that are full of litter and rubbish and things floating in the sea.

Los Alcazares beach is incredibly clean with litter bins every hundred meters and the sea looks clear to me, however, the storms and subsequent run off in 2016 led to the town beach losing its Blue Flag status.

If beaches are your thing then Los Alcazares has a lovely 5 mile stretch.

Andy

Puerto Mazarron has a lovely blue flag sandy beach and prices are very reasonable. 

The beaches l along Mar Menor are lovely..dont let odd comments put you off....look a lttle inland from the beach areas in Los Alcaares, Santiago de la Ribera or a little further along towards Lo Pagan....depends on how busy or quiet you want it!

Los Alcazares beaches are well managed, with nightly grooming in the summer, with plenty of rubbish bins and a team of four people removing litter, all day.

Water visibility is the best its been in the last five years, for sure.

The Blue flags were lost after the Dec 2016 flood, but should be back for this season

I agree the beeches at p de Mazarron are great but It's a long way to go from Los Alcazares area just for a paddle

And/or, from Lo Pagan the Med beaches of the Salinas nature reserve are relatively easily accessible (especially if you cycle).

Have you looked further afield, San Juan de los Terreros. has a beautiful sandy beach and shallow water into the sea.

 (Águilas is neatest big town) 

I bought in Los Narejos 4 years ago and love it. It's so convenient to everything (shops, supermarkets, cafés, restaurants and the sea which is a 15 minute walk). We have a car so driving to the Mediterranean beaches at Mil Palmares is only 15 minutes. We also have bicycles and one of the beauty's of the area is it's really flat so you can easily cycle to the other Mar Menor beaches at Lo Pagan and Santiago de la Riberra. Can't fault it.