For the second dive we followed the "Bat cave" line, surfacing midway through the dive to look at the open air cavern and check out the bats there. Really great.
At the lowest point in the dive we saw a halocline beneath us, where the seawater began mixing with the fresh water. This was a much mirkier halocline than the one I remembered from Temple of Doom many years ago. In that case, there was a defined barrier between the two water densities. I don't know what prohibited that from forming here.
Poncho aborted the dive pretty early on due to equalisation problems with his ear.
Dive was timed well as we hardly saw any other divers, despite the park starting to get busy.
It is election day in Mexico today, so plenty of people out and about queueing to vote. What's more, all the bars and pubs are closed. Even some of the channels on TV have been suspended.