Piscinas Municipais de Lagos / Lagos em Forma

This is a lovely pool, with very friendly (English-speaking) staff. It was quiet and ideal for lane swimming when I visited, and both times I've been there, I've had an entire lane to myself.

Bring your own lock for the lockers. Men's boxer-style swim trunks are not permitted; briefs (think Speedos) and jammers are the rule. A swimming hat is also required.

This is an excellent indoor facility. It includes a 25m competition pool and two other pools for teaching and children. The admission includes not only use of the pool but the weight room as well. I swam laps here on a Saturday afternoon and only five of the eight lanes were occupied. Reception was friendly and spoke English; they explained the rules (padlock, cap, Speedo, and flip flops required) and showed me how to navigate the entrance turnstile and which locker room to use.