Apart from the wonder of the Algarve that is Benagil that deserves its own separate section, there is great paddling under the sandstone cliffs all the way from Portimão to Albufeira. There are put-ins at the southeast of Portimão estuary, Carveiro beach and other places. Praia da Marinha has some classic rock formations but also lots of steps. For a longer tour you can continue all the way to Armação de Pera for some beaches and cliffs that are similar, but a little more remote and secluded than the equivalent in Lagos and Ponta da Piedade. Some of them are naturist beaches.
Pera has a long sandy beach, then the cliffs return with some interesting blowholes to explore on the outskirts of Albufeira. Towards the end there is a particularly interesting beach section – The Swallow’s Nest Beach, Albufeira.
There is also a pleasant inland paddle from Portimão to Silves, described here: Inland Paddles.