The mouth of Arade river offers a natural harbor, several kilometers long, sheltering many recreational and fishing ships.
Maybe because of that, Portimão challenges Nazaré as the best places in the world to eat sardines.
However, Portimão, though staying a little inland, is also the hub to access some of the best beaches of Algarve.
My first experience in Algarve was camping in a free campground just behind the beach (Oh, those good days with lots of free space in Algarve...).
We couldn't support the heat (and the absence of toilets) and alternated, one day there and another in a hostel, leaving the tent in place. I enjoyed the beach - small, secluded, safe, nice.
Many years later I went there with my family. No more free campgrounds, lots of construction, but the same nice beach easily accessed. The problem, that time, was an attack of thousands of black small insects from north Africa (not mosquitoes) that forced us to abandon the beach early than planned.
I will let you know about my third time in this nice beach, a couple of kilometers west of Portimão.
Protected by the breakwater of Portimão, this beach is perfect for children.
Going a little further, after the breakwater there a smaller beach also calm and protected by the cape. Crossing it, the open sea has a few beaches, some of them with private concession and with many people, some other harder to reach and almost empty.
Lots of choice as an alternative to the wide, steep and crowded Praia da Rocha.