Polarized and GND Filters Together

Im currently staying in Tanzania for the next few months and the beach scenes are really throwing me off.

I have a Hoya Polarizer on one lens but its not really doing the job.

Has anyone used a GND filter combined with a Polarized filter for beach scenes, and which Polarize filter would allow another filter to be attached to it?

I have used my circular polarizer along with my GND filters. I know alot of guys will tell you that this is a "no no". I have actually had pretty good luck with this combination.

I did that last night for some sunset shots. I haven't them worked on them yet but the polarizer did the job of giving/cutting me the extra stop.