Underwater Communication

Table of Hand Signals

A diver cannot talk underwater unless he is wearing a full-face mask, but divers can communicate, using hand signals. It is said that if a diver "signals to his buddy regularly during a dive, this will ensure that they remain in close contact and that they can easily notify each other in case problems occur."; a diver should repeat any sign that is not clear to his buddy, and acknowledge every signal that he or she makes with an "OK" signal to show that he understands.

No.	Signal	Meaning	Comment
1.	Hand raised, fingers pointed up, palm to receiver.	STOP	Transmitted in the same way as a traffic police officer’s STOP
2.	Thumb extended downward from clenched fist.	GO DOWN or GOING DOWN
3.	Thumb extended upward from clenched fist.	GO UP or GOING UP
4.	Thumb and forefinger making a circle with three remaining fingers extended (if possible).	OK! or OK?	Divers wearing mittens may not be able to extend 3 remaining fingers distinctly.
5.	Two arms extended overhead with finger tips touching above head to make a large O shape.	OK! or OK?	A diver with only one free arm may make this signal by extending that arm overhead with finger tips touching top of head to make the O shape. Signal is for long-range use.
6.	Hand flat, fingers together, palm down, thumb sticking out, then hand rocking back and forth on axis of forearm.	SOMETHING IS WRONG	This is the opposite of OK! The signal does not indicate emergency.
7.	Hand waving over head (may also thrash hand on water).	DISTRESS	Indicates immediate aid required.
8.	Fist pounding on chest.	LOW ON AIR	indicates signaler's air supply is reduced.
9.	Hand slashing or chopping throat.	OUT OF AIR	Indicates that the signaler cannot breathe.
10.	Clenched fist on arm extended in direction of danger.	DANGER

Make sure that you review hand signals with your dive partner before your dive so there is no miscommunication underwater. 

Just For Fun

Controlling Buoyancy Underwater

To dive safely, divers must control their rate of descent and ascent in the water. Ignoring other forces such as water currents and swimming, the diver's overall buoyancy determines whether he ascends or descends. Equipment such as the diving weighting systems, diving suits and buoyancy compensator's can be used to adjust the overall buoyancy. When divers want to remain at constant depth, they try to achieve neutral buoyancy. This minimizes gas consumption caused by swimming to maintain depth.
The downward force on the diver is the weight of the diver and his equipment minus the weight of the same volume of the liquid that he is displacing; if the result is negative, that force is upwards. The buoyancy of any object immersed in water is also affected by the density of the water. The density of fresh water is about 3% less than that of ocean water. Therefore, divers who are neutrally buoyant at one dive destination (e.g. a fresh water lake) will predictably be positively or negatively buoyant at destinations with different water densities (e.g. a tropical coral reef).

The main thing to remember with buoyancy is that you should always check your weight at the beginning of the dive so that you are comfortable throughout the entire dive. Use your fins to swim and hold your arms across your chest as shown in this picture. You will loose a lot less oxygen and be able to dive longer. Remember that buoyancy takes time to adjust to at first so don't get frustrated. In time you will learn all the tricks of the trade.

Octopus Fun

• Octopuses are boneless creatures. They don't have a vertebral column, that is, they are invertebrates. The beak which is in the shape of a parrot beak, is the only hard structure in their body. Due to this reason, their bodies are extremely flexible and they can squeeze through incredibly small spaces.
• Octopuses vary in size depending upon the species. While those found in tropical waters are small, octopuses of the colder seas are larger in size. The giant Pacific octopus is the largest amongst all the members of the group and are known to grow as large as 23 feet. However, most octopuses are smaller in size. Usually they grow up to 10 feet and weigh around 55 ponds. Females are smaller than the males.
• An interesting octopus fact is that these sea creatures have three hearts. Two hearts pump blood through the gills whereas the third one pumps blood through rest of the body.
• The color of octopus blood is blue.
• The octopus is a predator. It hunts at night. Its favorite food are crabs, mollusks and crayfish.
• Octopuses are preyed upon by sharks, dolphins, morays and conger eels.
• These eight legged creatures have highly developed sense of sight that helps them to hunt efficiently in the low light levels of the deep waters. They also have an excellent sense of touch. Octopuses have sensory receptors at the bottom of their suckers that enable them to "taste" whatever they touch. They are, however, deaf.
• Male octopuses die within a few months of mating. However, males of larger species live longer. Female octopuses die soon after their eggs hatch.
• The most remarkable octopus fact is that they have a number of defense mechanisms. They can change the color of their body to merge with the surrounding that helps them to stay invisible from prey or predators. The first instinct of an octopus, when threatened, is to flee. Octopuses are known to eject a cloud of black ink when attacked by a predator. Sometimes they may also shed an arm to escape a predator. The lost arm regrows in some time.

Yongala Australia Shipwreck

In Australia there is one of the largest most visited shipwrecks. The Yongala is a shipwreck off the coast of Queensland. Full of life you may see manta rays, sea snakes, octopuses, turtles, bull sharks, tiger sharks, clouds of fish and spectacular coral. I would love to see more pictures of this site, if any of you have some please feel free to share! 

Diving with Sharks

At first when you see a shark its your natural reaction to tense up and freak out unless you have been diving around sharks for a while. Just remember that the more excited you get the more oxygen you use, so calm down and enjoy the sharks. Here are two of my personal videos of swimming with white tip sharks. Enjoy

Shark Facts!!

Sharks have between 5 and 7 gill slits on each side of their body in front of their pectoral fins. Bony fishes only have one pair. Having many exposed gill slits probably helps transfer more oxygen into their blood faster which allows them to swim very fast when they need to.


Most shark's skin is covered in small denticles instead of scales. Denticles are a lot like teeth. They have dentine in the centre and enamel on the surface. This makes shark's skin very tough and abrasive like sandpaper. The shape and position of some shark's denticles also helps reduce friction so that they can slip through the water easier.


Sharks have an extra sense that is able to detect tiny electric fields. They can use this to find food that is buried or to search for animals to eat in the dark or in turbid water. Sharks and rays make up the sub-class of fishes called elasmobranches. This sub-class is part of a class of cartilaginous fishes called Chondrichthyes which also includes chimaeras (ratfishes).


How dangerous are sharks?

• Sharks are usually very wary of people and most sharks will swim away long before you see them.
• There are nearly 500 species of sharks but only a few are likely to be involved in an attack. Some of the more dangerous sharks include the Great White Shark, the Tiger Shark, and the Bull Shark.
• Sharks do not normally treat humans as food. If they did, it would be very easy for them to eat all of the people who play in the water at the beach because they are much better swimmers than we are. Most scientists agree that attacks are usually the result of mistaken identity or the sharks feeling threatened because they are cornered. In places like California where there are a lot of White Shark attacks on surfers, scientists believe that the sharks think that the surfers look like seals or sea lions.

What do sharks eat?

• Sharks and rays have a very varied diet. They are carnivores which means that they eat animals rather than plants and algae. Some sharks commonly eat bony fishes, crustaceans (crabs, lobsters, and other animals with an external skeleton), mollusks (snails, sea slugs, octopus and squids), and different types of worms. 
•  A shark's diet is often determined by its habitat. For example, sharks that live out at sea (pelagic sharks) are more likely to eat fish and squid because that is all that is available.