Go Sport in Villagio sell some hiking and camping gear - camel-paks, etc.

There are some shops in Souk Wakif that sell hiking/camping gear. They are on the right hand side of the main walking area as you walk away from the restaurant area.

As first poster said, Sun, Sand and Surf in City Centre shopping centre sell Columbia stuff as well as North Face stuff. They have good sales every so often.

Hope this helps.