IDC Underwater Navigation & Dive Planning

Question 1

What are the two primary methods of underwater navigation taught in PADI training?

Accepted Answer

Natural navigation (using environmental features) and compass navigation (using a magnetic compass)

Answer

GPS and electronic chart navigation only

Answer

Following a guideline or dive flag

Answer

Surface support radio communication only

Question 2

How do you calculate the reciprocal heading on a compass when navigating in a straight line?

Accepted Answer

Add 180 degrees if the heading is below 180, or subtract 180 degrees if it is 180 or above

Answer

Multiply the original heading by 2

Answer

Divide the original heading by 2

Answer

Use the original heading plus 90 degrees

Question 3

What is a 'natural navigation check-in point' and how should divers use it?

Accepted Answer

A distinctive underwater landmark that divers identify to confirm their position during a dive

Answer

A location marked with a buoy line for navigation practice only

Answer

A feature only used by dive guides — not relevant for recreational divers

Answer

A surface landmark used before descending

Question 4

What key elements should a dive plan include?

Accepted Answer

Maximum depth, dive duration, air turnaround pressure, buddy assignments, entry/exit procedures, signals, and emergency contacts

Answer

A marketing document for the dive shop

Answer

A sketch of the dive site made after the dive

Answer

Only the no-decompression limit calculation

Question 5

What does the 'rule of thirds' refer to in dive air management?

Accepted Answer

Using one-third of the air supply for the outbound journey, one-third for the return, and keeping one-third in reserve

Answer

Spending one-third of the dive at maximum depth

Answer

A navigation technique dividing the dive site into three zones

Answer

The maximum visibility range before a buddy is considered lost

Question 6

What factors should a PADI Instructor consider when selecting an appropriate dive site for student training?

Accepted Answer

Conditions (current, visibility, temperature), entry/exit safety, presence of hazards, depth appropriate for training level, and proximity to emergency services

Answer

Only depth and visibility — other factors are secondary

Answer

Distance from the dive shop and parking availability

Answer

Only the preferences of the majority of students in the class