Are you quite sure you mean Portugal?

The rock/river activities would be mostly located in the central and northern parts of the country and in March the temperature would probably rule out the sea/ beach activities. You need to find your way round Google, Portugal is a big country not just the Algarve. It's a long north-south strip and the whilst the weather on the Algarve might be pleasantly spring like in March it will be litle better than England in the north. As a starter try http://www.portugalkayak.com/web-content/home.html for locations. And bear in mind that if the location is in the Beiras then Faro airport is not a good idea! Lisbon or even Porto would have to be used.

You won't find anywhere with jetskis, kayaking (except in the rivers up north) dune buggies etc in March as the sea is too rough and too cold and there are not enough people. They don't happen until May at the earliest.

Even quad biking down here is probably out, as the ground is too wet under foot (under wheel?) but there are quad bike tours available in the Algarve.

As the previous poster said, Portugal is 400 miles long and if you want rock climbing and similar activities you are better off heading for Porto, which is 350 miles nearer the mountains than Faro. Up in those mountains in March it can be cold, wet and horrible.

Example - as I write in Albufeira it is 17C and fairly bright and sunny, up there it is 7C and raining.

thanks some useful information there