Whale sharks rule. We saw over 300 of them today!
But first, here are 4 images from two dives at Kulkulkan and Chac-Mool cenotes. I only took my still camera in for 2 dives because I was focused in 3D video, but the caves were too beautiful not to get a few still shots.

A sign in a halocline warns divers of impending death upon further exploration of the beginning of a long cave system (Cenote Kulkulkan, Mexico)

Sterling Zumbrunn contemplates his future while in a shimmering halocline at Cenote Kulkulkan, Mexico.

Sterling Zumbrunn at Cenote Kulkulkan, Mexico

Cave diver at Cenote Chac-Mool, Mexico
Our group (me, Sterling Zumbrunn, Wolcot Henry, Heidi Connal, Alexis Tabah and Nathalie Ssi-Yan-Kai) had a one-day overlap with Shawn Heinrichs, Rob Stewart, Bob McNerney, and Brian, who had been here for the last trip out to the whale shark aggregation.
There is simply no good way to photograph 300 whale sharks, but I do have some topside images from the tuna tower that probably show 50 in a frame.
I shot mostly video today, but here are a few stills:

Two whale sharks (Rhincodon typus) feed in a bonito spawning event off of Isla Mujeres, Mexico

A whale shark (Rhincodon typus) feeds in a bonito spawning event off of Isla Mujeres, Mexico

A whale shark (Rhincodon typus) feeds in a bonito spawning event off of Isla Mujeres, Mexico

A silhouette of a whale shark (Rhincodon typus) feeding in a bonito spawning event off of Isla Mujeres, Mexico