Anchorman

For as much as I love natural history, my husband feels the same about archaeology. His favorite dives are on historical shipwrecks, especially those with inner passages to be explored. He loves finding the engine room, seeing how the ship was run, and as a friend of ours jokes, "counting rivets." So when one of the employees at our dive resort mentioned there were some 19th-century anchors at 60 m (200 ft) deep at the southern end of the island, I knew we were in for a long, deep dive. 

This species was really common at depth. I think it's the 
feather black coral (Plumapathes pennacea).

I got certified for trimix diving just a few months ago, and I must admit, I was pretty excited to put those skills to use again. We planned our profile, ran simulated scenarios, and requested our gas mixes from the tech shop. The weather was pretty good and the waves weren't too big, so we strapped on our tanks and headed down the slope. 

I was enthralled. Not by the anchors - I barely noticed them at first - but by the invertebrate community at 60 m deep. Little light from the surface penetrates this far, so the coral community is sparse. Instead, we found large red barrel sponges (Neofibularia nolitangere) and lots of sea fans (Iciligorgia schrammi). 

My husband was occupied with different things. In the short time we had at depth, he found 6 or 7 large anchors, a ballast brick, a large chain, and a giant shackle. I was actually impressed by his internal metal detector, because he found all that in 40 minutes. 

My husband, Carl, next to one of the submerged anchors

The site we were at is called Red Slave, and the story behind that name involves some history. First of all, Bonaire's desert climate and intense sun make it the perfect location for sea salt manufacturing. There are giant salt flats on the southern end of the island - acres-wide shallow ponds that are flooded with seawater - and as the water evaporates, the salt remains. In the 19th century, salt was loaded into seagoing vessels by slaves at four sites marked by colored obelisks. Each color corresponded to a different grade of salt, so vessels would pull up to the site corresponding to the grade they wanted. Color-matching huts were constructed at the loading sites so that slaves had a place to rest and store personal belongings. Slavery ended in Bonaire in 1863, but the obelisks and huts are still there. The hardware we saw at depth most likely originated from vessels that anchored near shore to be loaded with salt in the 19th century. 

After our short stay at depth, we had a long series of decompression stops ahead of us. Deco can be pretty boring, but admittedly, watching fish swim around a coral reef is preferable to some other decompression stops I've had in my life. The most challenging part of the dive came right at the end. While we were underwater, the wave surge increased - to the point that it was difficult to climb out of the water. Further complicating the situation was the fact that Carl and I both had multiple stage tanks hanging off of us. At one point, I slipped on the rock and spent a few minutes just getting pounded by waves. Some compassionate fellow divers helped us lift our tanks, shed our fins, and crawl out of the surf. We were very grateful! 

Overall, it was an incredible dive, and I was glad we got to see such a deep part of Bonaire's coral reef and a cool part of the history!