PADI The Aquatic Environment 2 — Questions and Answers
Question 1: What causes tidal patterns in the ocean?
- Solar radiation heating the water surface
- The gravitational pull of the moon and sun (Correct answer)
- Prevailing wind patterns over the ocean
- Differences in ocean salinity levels
Correct answer: The gravitational pull of the moon and sun
Tides are primarily caused by the gravitational forces exerted by the moon and, to a lesser extent, the sun on Earth's oceans.
Question 2: Which type of current is created when dense, cold water sinks and displaces warmer water upward?
- Longshore current
- Rip current
- Thermocline current
- Convection current (Correct answer)
Correct answer: Convection current
Convection currents form when temperature differences cause denser cold water to sink, displacing lighter warm water upward in a circulatory pattern.
Question 3: What is the primary hazard of diving in areas with kelp forests?
- Kelp releases toxins harmful to divers
- Kelp can entangle divers and restrict movement (Correct answer)
- Kelp forests attract large predatory sharks
- Kelp absorbs oxygen from the water column
Correct answer: Kelp can entangle divers and restrict movement
Kelp fronds can entangle equipment or limbs, so divers should move slowly and deliberately, and know how to escape entanglement by rolling or backing out.
Question 4: A halocline is a layer in the water column characterized by a rapid change in:
- Water temperature
- Light penetration
- Salinity (Correct answer)
- Current speed
Correct answer: Salinity
A halocline is a distinct layer where salinity changes sharply with depth, often creating a visual blurring effect that divers can observe at the boundary.
Question 5: Which wave characteristic describes the horizontal distance between two successive wave crests?
- Wave height
- Wave period
- Wave wavelength (Correct answer)
- Wave amplitude
Correct answer: Wave wavelength
Wavelength is the horizontal distance measured from one wave crest to the next successive crest.
Question 6: When diving in areas with boat traffic, which practice is most important for diver safety?
- Surfacing far from the dive entry point
- Towing a surface marker buoy (SMB) when ascending (Correct answer)
- Staying at depth until the boat traffic clears
- Wearing brightly colored fins for visibility
Correct answer: Towing a surface marker buoy (SMB) when ascending
Deploying a surface marker buoy (SMB) during ascent alerts boat operators to a diver below and marks the surfacing location, significantly reducing collision risk.
Question 7: What is a 'spring tide' and when does it occur?
- A tide that only occurs during spring season
- An exceptionally high or low tide occurring at new and full moon (Correct answer)
- A rapid tidal current created by underwater springs
- A moderate tide occurring during quarter moon phases
Correct answer: An exceptionally high or low tide occurring at new and full moon
Spring tides occur during new and full moon phases when the sun, moon, and Earth align, combining gravitational forces to produce the highest high tides and lowest low tides.
PADI The Aquatic Environment 2
What causes tidal patterns in the ocean?