If you like James Clemens, you should read James Rollins, seeing as how they are the same person. His earlier books are reminiscent of Jules Verne and other classic novels, but starting in the third book, he really found his own voice. The first couple he wrote are stand alones, but he did start on a series called Sigma Six. He is a great author and a real nice guy, I used to keep up email communication with him. Another good writer is Matt Reilly who writes in the action adventure genre as well.