Lots of whale sharks now. Im very fortunate to be able to swim on a weekly basis and get up close and personal from June till sept photographing and doing tours. Seems like the whale shark is changing its diet !
Hola Vaga. You can walk around Isla Mujares and book there for whale sharks no problems. Most of the cenote diving is done around the Tulum area. Check out Playa Scuba or Yucatek Divers in Playa Del Carmen. Of course Cozumel has great diving! Other than cenotes It is by far better than the Mainland.
I think you can only use 1 filter with the 94 degree dome port since the retrofit to fix vignetting. I believe you can use 2 filters on the other available port ( macro dome). You could always put the red filter directly to the camera and the macro on the drop down filter. I will put a macro on the drop down and use lights so no need for colored filter.