This is part of our 100 Things in 2014 challenge. Here’s the full list.

For the 12th day of Christmas, I gave Becky a swim with a whale shark. We got up early and drove two hours to La Paz, squoze into wetsuits, and got on a boat.

We rode about 10 minutes over choppy seas, and spotted some really big fish.

…then we drove out in front of one and jumped in the water! The trick is to start swimming the direction the shark is, and keep going as fast as you can. These guys look like they’re just moseying, but they’re fast.

It’s hard to see in these photos just how huge these animals are. I swam above and alongside one for a good 5 minutes, and it was so big I couldn’t see the tail when I was near the head. They must have been about 30 feet long.

We had actually found a whole school of them. There were at least 5 in our area, which in kind of interesting, since they’re solitary creatures.

Every now and again, one of them would stop, come close to the surface, and open its mouth. These are their feeding grounds, so when they swim through a cloud of plankton, they suck in a gallon of water every 4 seconds and filter out the food. Like a giant wet vacuum, really. Our guide warned us not to swim directly away from them when they’re doing this, since you’d be pushing water into the shark’s mouth, and it would want to move closer to you.

Becky was terrified — she has a thing about large animals, and another thing about the open ocean — but she bravely pushed through, and she’s glad she did.

This was an incredible experience. Our adventure company is locally owned and really good, and our guide actually has a college degree in eco-tourism, so he actually told us how to take care of the animals, instead of ruining their day. As a bonus, we had a five-porpoise escort for a couple of minutes on our way back to the marina! Then we ate tacos. It was a good day.