From here you will drive to a large parking area at the very back of the park. Take the speed limit signs seriously; they mean it. From here it is a 400-foot walk to either the main spring or Catfish Hotel.

• The main spring is a shallow basin where the cave finally exits with fire-hydrant-like force. It is closed to divers during the winter when manatees are in residence. It is about a ten-minute dive at most. Divers will frequently jump in here after diving Catfish Hotel to burn up any remaining air and rinse off any residual duckweed.

• Catfish Hotel is the main dive site for open-water divers. It is an offset sinkhole approximately 125 feet across at its widest point. The north side is a slightly overhanging wall that drops to depths of around 50 feet at a large cavern entrance. Facing this entrance is a steeply-sloping bottom covered in tree trunks and algae.

• At the end of the stairs is a concrete platform that is usually underwater — and hidden beneath duckweed. Water levels can vary greatly so enter cautiously. Backing in on your knees is best. Attempting anything like a giant-stride entry is a good way to break something.

• Visibility in Catfish Hotel can vary greatly. Sometimes you can see almost from one side to the other. At other times it can drop to as little as 10 to 15 feet.

• The most interesting part of the cavern is the first 20 or so feet, which is adequately illuminated by daylight. Past this is a strong current that can suck you away to someplace you do not want to go. Follow the no-lights rule and you will be okay.

• Manatee Spring will remain open when many other Suwannee River sites have flooded out. However, should the water get high enough, the park will close due to an influx of gators. It’s best to check the park website ahead of time.

There are mens’ and ladies’ rooms on site but no air fills or gear rental. Bring what you need with you.

As the photo shows, Catfish Hotel is covered with a layer of duckweed. This looks, at first glance, like pond scum but it is really the world’s smallest flowering plant. Most of the time it has the consistency of finely chopped salad greens.

• The upside of diving under duckweed is that, when your bubbles break the surface, sunlight will stream through, creating some very dramatic effects.

• The downside is that, if you are not careful, you can emerge from the water coated head to toe, doing a pretty good impression of Swamp Thing.

This is preventable, though. All you need to do is conduct your safety stop as close to your exit point as possible. When you surface, you will most likely discover your bubbles created an open spot in the duckweed through which you can exit, largely duckweed-free.

• If you fail to rid yourself of duckweed before exiting the water and can’t rinse off at the main spring, there is an outdoor shower located near the top of the stairs.

Entry fees are modest — typically around five to six dollars per vehicle. Florida residents and frequent visitors may want to get an annual pass. This can save you money.

Be aware that is no dive center at Manatee Springs. The closest place to get equipment rentals and air fills is Blue Grotto, 30 miles away.