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TDI – Overhead Environment / Cavern Diver Course
Introduction
This course is designed to develop the minimum shills and knowledge for cavern and overhead environment diving within the limits of light penetration; in addition outlines specific hazards associated with cave diving. The Cavern Diver Course in not intended to provide instruction for cave diving environments. The objective of this course is to train divers in the proper planning, procedures, techniques and hazards of cavern diving.

Qualifications of Graduates
Upon successful completion of this course, graduates may engage in cavern diving activities without direct supervision so long as the following limits are adhered to:
1. Daylight and emergency ascent zone, i.e. within sight of the surface entrance.
2. Sixty one (61) linear meters / two hundred (200) linear feet from the surface.
3. Forty (40) msw / one hundred thirty (130) fsw maximum depth.
4. Twelve (12) meter / forty (40) feet visibility (minimum).
5. No decompression diving.
6. No restrictions (no areas too small for two (2) divers to pass side-by-side).
7. Safety stops as appropriate or necessary.
Upon successful completion of this course, graduates are qualified to enroll in:
1. TDI Introductory Cave Course.

Who May Teach
Who may teach this course:
1. Any active TDI Cavern Instructor may teach this course.

Student – Instructor Ratio
Academic:
1. Unlimited, so long as adequate facility, supplies and time are provided to insure comprehensive and complete training.
Confined Water (Swimming pool-like conditions):
1. N/A.
Open Water (Ocean, lake, quarry, spring, river or estuary):
1. A maximum of four (4) students per active TDI Instructor are allowed. The ratio should be reduced as required due to environmental or operational constraints.

Student Pre-Requisites
The student must:
1. Be at least age eighteen (18) or fifteen (15) with parental consent.
2. Show proof of a minimum certification as a certified diver with a minimum of twenty (20) dives.

Course Structure and Duration
Open Water Execution:
1. Three (3) dives with a total bottom time of eighty (80) minutes conducted in two (2) different sites.
Course Structure:
1. TDI allows instructors to structure courses according to the number of students participating and their skill level.
Duration:
1. The minimum number of classroom and briefing hours is six (6).

Administrative Requirements
The following is the administrative tasks:
1. Collect the course fees from all the students.
2. Ensure that the students have the required equipment.
3. Communicate the training schedule to the students.
4. Have the students complete the Liability Release and Medical history forms.
5. The Instructor should review the Liability Release and Medical Forms before starting on the course.
Upon successful completion of the course the Instructor must:
1. Complete the Student Registration Form and send the Registration Form to TDI HQ.
2. Award card and certificate.

Required Equipment
The following are required for this course:
1. TDI Cavern and Cave Manual.
The following equipment is required for each student:
1. Primary cylinder - volume appropriate for planned dive and student gas consumption.
2. Regulator with pressure gauge and alternate air source.
3. Buoyancy Compensator with power inflator.
4. Exposure suit adequate for cavern environment.
5. Mask and fins, taped as required - NO snorkel.
6. Line cutting device.
7. Two (2) battery powered lights with burn time suitable for the planned dive time.
8. Computer or watch (bottom timer) and depth gauge.
9. Line reel.

Required Subject Areas
The TDI Cavern and Cave Manual is mandatory and the NSS - Cavern Diving Manual, NACD - The Art of
Safe Cave Diving and CDAA - Cavern / Sinkhole Manual are recommended for use during this course but instructors may use any additional text or materials that they feel help present these topics.
1. Policy for Cavern Diving.
2. Environment Types
A. Cavern.
B. Wreck.
C. Other.
3. Environment Conditions
A. Bottom.
B. Ceiling.
4. Accident Analysis.
5. Psychological Considerations.
6. Equipment Considerations
A. Cylinder options.
B. Regulator options.
C. Buoyancy compensator / harness options.
D. Reel options.
E. Proper weighting.
7. Body and Buoyancy Control.
8. Swimming Techniques.
9. Problem Solving
A. Body positioning (trim).
B. Buoyancy control.
C. Emergency procedures.
D. Line following.
E. Propulsion techniques.
10. Review of Dive Tables and Decompression Avoidance.
11. Silting Conditions.
12. Local Access Requirements.

Required Skill Performance And Graduation Requirements
The following land drills must be covered during this course:
1. Guideline Use.
2. Guideline Following.
3. Emergency Procedures.
The student must complete the following in-water skills during cavern dives:
1. Demonstrate adequate pre-dive planning.
2. Safety drill on each dive, air sharing on at least one (1) dive a day.
3. Demonstrate buoyancy compensator use and body positioning via weighting and distribution.
4. Demonstrate specialized propulsion techniques.
5. Demonstrate guideline and line reel use.
6. Demonstrate understanding of light signals.
7. Explore cavern.
8. Demonstrate Emergency skills.
9. Follow line while sharing air.
10. Follow line with eyes closed.
11. Follow line with eyes closed and sharing air.
In order to complete this course, students must:
1. Satisfactorily complete the TDI Overhead Environment / Cavern Diver written examination.
2. Complete all land drill and cavern dive requirements safely and efficiently.
3. Demonstrate mature, sound judgment concerning dive planning and execution.
Updated 9 May 2003