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Course Outline

The ocean and its corals are a very popular type of diving environment. There are many other types of dive sites, and depending on the area in which you live, you may be able to enjoy “local diving.” Some dive sites may involve extra experience, equipment, and training, but many may not. Your local dive center is best equipped to advise you regarding the diving in your area.

Sponge Gardens

Many people dive in subtropical and temperate waters in places all around the world. These diving sites have many alternatives to the coral environments that are seen in the tropical areas.

Sponge gardens are very common in cooler waters and have a large variety of colors, shapes, and species. These are often home to many kinds of fish and create an ecosystem that is quite diverse. Sponges are delicate filter feeders. You should take good control of your buoyancy when diving around them so that you do no damage.

Rivers and Estuaries

Often, divers enjoy exploring different environments such as freshwater rivers or estuaries where rivers join the ocean. There will be many different kinds of animals quite different to those you’ll see in the ocean. This can be an exciting type of diving but can involve currents or swift water movement. Be aware of the hazards, and remember to dive well within your training, experience, and comfort zone. Never overestimate your ability to manage challenging conditions. If you have to face a challenging condition, borrow a line that many rebreather divers use: If in doubt, bail out. It is much better to be on the surface wishing you were in the water rather than the other way around.


There are many places where the ocean is a long day-trip away, while a lake with a diving area is nearby. Some lakes are very clear, but others are not. For example, fallen trees and forest vegetation leach tannins into lake water. When tannins leach out, they discolor water, which may seriously limit visibility and make it extremely difficult to keep in contact with your buddy or dive professional. Diving in these conditions to almost any depth is essentially a night dive. Treat these dives as such. And remember that if you do become separated from your dive partner, spend a short time looking around for them. If your dive partner has disappeared, surface and wait for him or her to appear.

Lakes are usually freshwater, so they will have a variety of freshwater animals to see. These animals include crayfish, bass, pike, trout, and many other species of bony fish. If you are into watching smaller creatures, keep an eye open for small crustaceans. They make a fascinating study, and hanging motionless watching nature unfold is excellent “buoyancy training.”

Speaking of which, care must be taken near the bottom of lakes because many have a very fine silt bottom that can create low visibility very fast. Keep off the bottom and keep your fins out of the muck.

Freshwater Cave Systems

Cave systems definitely require extra training but can be beautiful and exciting places to dive. Often, there are colorful formations from a time when the cave was a dry system. Stalagmites, stalactites, crystal columns, flowstones, soda straws, and other forms of “cave furniture” can be seen. There are also whole unique families of animals that live in low-light conditions, including blind cave shrimp that have no pigment, so their bodies are transparent.

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