Diving Environment

Objectives• Identify environmental conditions, which vary from region to

region.• State the importance of an area orientation and list in order of

preference three sources for obtaining an orientation.• Describe and discuss 4 effects of waves on a diver and describe

techniques for dealing with each.• Name three common types of currents and describe techniques

for dealing with each.• Describe how to get out of a current.• Discuss the effects of tides as they concern a diver.• Describe techniques for diving in kelp.• Describe the primary danger of rocks to divers, and three

techniques for preventing injury.• State two primary factors affecting visibility and recommended

techniques when diving in limited visibility.

Temperature

• Thermocline– An abrupt change in temperature at depth– Do not confuse with an increase in cold due

to suit compression

Temperature

• Upwelling– Seasonal condition in CA – Caused by wind

• Surface water is replaced by cold deep water.• Extremely cold from the surface to depth.• Extremely clean and clear.

• Post Upwelling– Plankton blooms

Area Orientation

• Importance– Protect you, marine life, environment– Enjoyable dive more likely

• Sources for area orientation– Active instructor

– This is your best source of information.

– Active divemaster or dive guide– Experienced local divers

Kelp

• General Techniques– Dive with a buddy– Move gently– Streamline gear– Save air – Pick path– Pay attention to navigation– Carry knife or shears

• Kelp is easily broken or snapped by hand• You can bite through kelp

Waves

• Primary cause– Wind

• Strength of the wind• Distance the wind blows over water (fetch)• Duration (period of time the wind blows without

interruption

Surge

Wave energy felt on the bottom.

• When wave size remains constant– depth increase surge will decrease.

• Moves in a circular or elliptical pattern.

Surge

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Surge

• Do not fight the surge.– When surge is against you, hold on to rocks

or kick to hold position.– When surge is with you, kick to make

progress.

• Surge is strongest toward shore.– Sand Transport

Surf

Area of breaking waves near the beach• Waves break when the water depth becomes

too shallow to support the wave

General Techniques• Get through the surf zone as quickly as possible• Keep control of all equipment• Follow the last wave of the set• Choose an appropriate entry/exit technique

When in doubt about your ability to handle the waves and surf,

DO NOT ATTEMPT THE DIVE!

Rocks

Primary danger is slipping • Injury prevention

– Wear protective clothing– Walk with care– Fend off

• Fingertip diving– Be very aware of surge. – Pick a spot to place your hand and fend off prior to

the surge pushing you into the rock. – If possible select a spot on the rock that is bare and

not covered

Visibility

• Factors which affect visibility– Turbidity

• Particulate matter in the water

– Light• Best time to dive is when sun is high in the sky

– Run-off– Pollution– Wind– Tides– Waves, Surge and Surf

Limited Visibility Techniques

• Good buddy techniques– Frequent checks– Physical contact– Positioning

• Dive lights

• Good buoyancy control– Avoid stirring up the bottom

Currents Near Shore

• Rip Current– A current running directly away from shore.– As a general rule, it is advisable to avoid rip

currents.– Choose entry and exit points that route you between

the currents.– Identified by dirty mushroom shaped patches of

water

• Longshore – Current that runs parallel to the beach.– Often strongest within the surf zone

General Techniques for diving in current

• Begin your dive against the flow of the current

• Hug the bottom

• Hold onto rocks or shelter in protected area

• Finish your dive up-current from the boat• Allow for the effects of the current on air

consumption– When beginning the dive against the current

either• Go farther than normal before turning around or• Look for the anchor or exit point early

Current

X 3000 psi 1750 psi

500 psi

Getting out of a current

• If a current is moving you in an undesirable direction, escape the current by swimming across the flow of the current

• This applies especially to– Rip current– Longshore current

Other Currents

• Standing Current– River or ocean currents– Require special training due to special

hazards

• Upwelling– Upwelling is considered a current although

its effects on divers are limited to temperature considerations.

Tides

• Daily rise and fall or ebb and flow of water

– Can be predicted• Tide tables available through government and

private agencies

Tides

• Visibility– Best visibility is at high tide– Worst visibility is at low tide– Choose time to dive and dive site accordingly

Tides

• Surf zone– Location of surf zone may vary with tide as

depth of water changes– Intensity of surf zone may vary with tide

• Currents– Tidal currents may be too strong to swim

against

• Develop local knowledge and knowledge of current diving

Marine Life

• Smooth gentle movements will allow you to get closer to the marine life.

• Abrupt, thrashing movements will frighten the animals away.

• Most injuries associated with marine life are defensive actions on the part of the animal

Conservation

• Local knowledge• Look but don’t touch• Buoyancy control• Fin control• Fish and game regulations• Body/gear awareness• Collect only appropriate items, at

appropriate locations and times

• No Collecting in Class!