WELCOME TO Halo Anilao Dive Resort's SCUBA WIKI
-special thanks to Wikipedia® 

the scuba

Safety and Rescue Facilities

Please be advised of the following facilities, Its better to be aware and prepared.

AFP Medical Center - Recompression Chamber 
V. Luna Road, Quezon City, Philippines 
Contact Person: Dr. Jojo Bernardo, M.D. 
Phone: +63 (2) 920-7183 Phone: +63 (2) 426-2701 local 8991 / 6445 

Cebu Recompression Chamber 
Central Command Station (VISCOM) Hospital 
Camp Lapu-Lapu, Lahug, Cebu City, Philippines 
Contact Person: Mamerto Ortega 
Phone: +63 (32) 310-709 Chamber 
Phone: +63 (32) 232-2464 to 68 local 3625 / 233-9942 

NOTE: Currently, there are four Philippine Coast Guard Search and Rescue Vessels (SARVs) with hyperbaric / recompression chambers on-board the vessels. 

Dr. Jose “Jojo” R. Bernardo M.D. 
AFP Medical Center V. Luna Road, Quezon City 
Tels.: +632. 920.71.83 / +632 426.27.01 local 8991 or 6445 

Dr. Benjamin "Benjie" Luna, M.D. 
Cardiologist-Internist, Asian Hospital, Philippines 
Phone +632. 815. 99.11 Extension 2123 Fax +632. 817. 56.01

Philippine Air Force, 505th Search and Rescue Group 
Villamor Air Base, Pasay City 
Tel: +632. 853.50.13 / +632.853.51.21

Philippine Coast Guard 
(Operations) Tel.: +632. 527.38.70 / Fax: +632.527.38.80
Coast Guard Air Group, Tel. +632.832.37.56




SCUBA Diving

Not to be confused with Self-contained breathing apparatus, which describes breathing sets used out of water.

Scuba diving ("SCUBA" originally being an acronym for self contained underwater breathing apparatus, now widely considered a word in its own right)[1] is a form of underwater diving in which a diver uses a scuba set to breathe underwater.[2]

Unlike early diving, which relied either on breath-hold or on air pumped from the surface, scuba divers carry their own source of breathing gas (usually compressed air),[3] allowing them greater freedom of movement than with an air line. Both surface supplied and scuba diving allow divers to stay underwater significantly longer than with breath-holding techniques as used in snorkelling and free-diving. Depending on the purpose of the dive, a diver usually moves underwater by swimfins attached to the feet, but external propulsion can come from anunderwater vehicle, or a sled pulled from the surface.


The first commercially successful scuba sets were the Aqualung open-circuit units developed by Emile Gagnan and Jacques-Yves Cousteau, in which compressed gas (usually air) is inhaled from a tank and then exhaled into the water adjacent to the tank[4]. However, the scuba regulators of today trace their origins to Australia, where Ted Eldred developed the first mouth piece regulator, known as the Porpoise. This regulator was developed because patents protected the Aqualung's double hose design. It separated the cylinder from the demand valve giving the diver air at the same pressure surrounding his mouth, not that at the top of the tank.

The open circuit systems were developed after Cousteau had a number of incidents of oxygen toxicity using a rebreather system, in which exhaled air[citation needed] is reprocessed to remove carbon dioxide. Modern versions of rebreather systems (both semi-closed circuit and closed circuit) are still available today, and form the second main type of scuba unit, most commonly used for technical diving, such as deep diving.


The term "SCUBA" (an acronym for self-contained underwater breathing apparatus) arose during World War II, and originally referred to United States combat frogmen's oxygen rebreathers, developed by Dr. Christian Lambertsen for underwater warfare.

The word "SCUBA" began as an acronym, but it is now usually thought of as a regular word—"scuba". It has become acceptable to refer to "scuba equipment" or "scuba apparatus"—examples of the linguistic RAS syndrome.


Types of Diving

Recreational diving and Professional diving

Scuba diving may be performed for a number of reasons, both personal and professional. Most people begin[citation needed] through recreational diving, which is performed purely for enjoyment and has a number of distinct technical disciplines to increase interest underwater, such as cave divingwreck divingice diving anddeep diving.

Divers may be employed professionally to perform tasks underwater. Most of these commercial divers are employed to perform tasks related to the running of a business involving deep water, including civil engineering tasks such as in oil exploration,underwater welding or offshore construction. Commercial divers may also be employed to perform tasks specifically related to marine activities, such asnaval diving, including the repair and inspection of boats and ships, salvage of wrecks or underwater fishing, like spear fishing.

There are a fair number of divers who work, full or part time, in the recreational diving community as instructors, assistant instructors, divemasters and dive guides. There is some controversy as to whether such recreational diving leadership personnel should be termed "professionals" or not.[citation needed] Several of the recreational training agencies include the word "professional" in their name, something that is ridiculed by others, who do not feel that the training programs that recreational leaders undergo and their rather short career length warrant the title.[citation needed]

In some jurisdictions the professional nature, with particular reference to responsibility for health and safety of the clients, of recreational diver instruction, dive leadership for reward and dive guiding is recognised by national legislation.[7][8]

Other specialist areas of diving include military diving, with a long history of military frogmen in various roles. They can perform roles including direct combat, infiltration behind enemy lines, placing mines or using a manned torpedobomb disposal or engineering operations. In civilian operations, many police forces operate police diving teams to perform search and recovery or search and rescue operations and to assist with the detection of crime which may involve bodies of water. In some cases diver rescue teams may also be part of a fire department, paramedical service or lifeguard unit, and may be classed as public service diving.

Lastly, there are professional divers involved with the water itself, such as underwater photography or underwater filming divers, who set out to document the underwater world, or scientific diving, including marine biologygeologyhydrologyoceanography and underwater archaeology.

The choice between scuba and surface supplied diving equipment is based on both legal and logistical constraints. Where the diver requires mobility and a large range of movement, scuba is usually the choice if safety and legal constraints allow. Higher risk work, particularly commercial diving, may be restricted to surface supplied equipment by legislation and codes of practice.

Moving and seeing underwater

Refraction and underwater vision

Main article: Underwater vision

A diver wearing an Ocean Reef full face mask

Water has a higher refractive index than air; it's similar to that of the cornea of the eye. Light entering the cornea from water is hardly refracted at all, leaving only the eye's crystalline lens to focus light. This leads to very severe hypermetropia. People with severe myopia, therefore, can see better underwater without a mask than normal-sighted people.

Diving masks and diving helmets and fullface masks solve this problem by creating an air space in front of the diver's eyes.[2] The refraction error created by the water is mostly corrected as the light travels from water to air through a flat lens, except that objects appear approximately 34% bigger and 25% closer in salt water than they actually are. Therefore total field-of-view is significantly reduced and eye–hand coordination must be adjusted.

(This affects underwater photography: a camera seeing through a flat window in its casing is affected the same as its user's eye seeing through a flat mask window, and so its user must focus for the apparent distance to target, not for the real distance.)

Divers who need corrective lenses to see clearly outside the water would normally need the same prescription while wearing a mask. Generic and custom corrective lenses are available for some two-window masks. Custom lenses can be bonded onto masks that have a single front window.

A "double-dome mask" has curved windows in an attempt to cure these faults, but this causes a refraction problem of its own.

Commando frogmen concerned about revealing their position when light reflects from the glass surface of their diving masks may instead use special contact lenses to see underwater.

As a diver descends, he must periodically exhale through his nose to equalize the internal pressure of the mask with that of the surrounding water. Swimming goggles are not suitable for diving because they only cover the eyes and thus do not allow for equalization. Failure to equalise the pressure inside the mask may lead to a form of barotrauma known as mask squeeze.[2][14]

Light underwater

Water preferentially absorbs red light, and to a lesser extent, yellow and green light, so the color that is least absorbed by water is blue light.[15]

Table of Light Absorption in pure water

Color Average wavelength Approximate depth
of total absorption Ultraviolet 300 nm25 m Violet 400 nm100 m Blue 475 nm275 m Green 525 nm110 m Yellow 575 nm50 m Orange 600 nm20 m Red 685 nm5 m Infra-red 800 nm3 m


Controlling buoyancy underwater

Diver under the Salt Pier in Bonaire.

To dive safely, divers must control their rate of descent and ascent in the water.[3] Ignoring other forces such as water currents and swimming, the diver's overall buoyancy determines whether he ascends or descends. Equipment such as diving weighting systemsdiving suits (wetdry or semi-dry suits are used depending on the water temperature) and buoyancy compensators can be used to adjust the overall buoyancy.[2] 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 volume of the liquid that he and his equipment aredisplacing; 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.[16] Therefore, divers who are neutrally buoyant at one dive destination (e.g. a fresh water lake) will predictably be positively or negatively buoyant when using the same equipment at destinations with different water densities (e.g. a tropical coral reef).

The removal ("ditching" or "shedding") of diver weighting systems can be used to reduce the diver's weight and cause a buoyant ascent in an emergency.

Diving suits made of compressible materials, decrease in volume as the diver descends, and expand again as the diver ascends, creating buoyancy changes. Diving in different environments also necessitates adjustments in the amount of weight carried to achieve neutral buoyancy. The diver can inject air into dry suits to counteract the compression effect and squeeze. Buoyancy compensators allow easy and fine adjustments in the diver's overall volume and therefore buoyancy. For open circuit divers, changes in the diver's lung volume can be used to make fine adjustments of buoyancy.

Neutral buoyancy in a diver is a metastable state. It is changed by small differences in ambient pressure caused by a change in depth, and the change has a positive feedback effect. A small descent will increase the pressure, which will compress the gas filled spaces and reduce the total volume of diver and equipment. This will further reduce the buoyancy, and unless counteracted, will result in sinking more rapidly. The equivalent effect applies to a small ascent, which will trigger an increased buoyancy and will result in accelerated ascent unless counteracted. The diver must continuously adjust buoyancy or depth in order to remain neutral. This is a skill which improves with practice.

Being mobile underwater

The diver needs to be mobile underwater. Streamlining dive gear will reduce drag and improve mobility. Personal mobility is enhanced by swimfins and Diver Propulsion Vehicles. Other equipment to improve mobility includes diving bells and diving shots.

Underwater Communication

A diver cannot talk underwater unless he is wearing a full-face mask, but divers can communicate, using hand signals. It is said[citation needed] 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.

Scuba diver training and certification agencies

Recreational scuba diving does not have a centralized certifying or regulatory agency, and is mostly self regulated. There are, however, several large diving organizations that train and certify divers and dive instructors, and many diving related sales and rental outlets require proof of diver certification from one of these organizations prior to selling or renting certain diving products or services.

The largest international certification agencies that are currently recognized by most diving outlets for diver certification include:


Halo Anilao Dive Resorts, Inc.
Brgy. Ligaya, Mabini, Batangas
Philippines, 4202


copyright 2016 © Halo Dive Resorts - All rights reserved




Scuba diving ("SCUBA" originally being an acronym for self contained underwater breathing apparatus, now widely considered a word in its own right) is a form of underwater diving in which a diver uses a scuba set to breathe underwater.