TDI Poseidon Rebreather - CCR MkVI/SE7EN Discovery

Silent Diving…..No Bubbles…..Closer interaction with Marine Life…..Longer Bottom Times…..Less deco….Warm moist recycled air.  Does all this, or even some of it, sound exciting?  If so the Poseidon CCR SE7EN may well be for you….

The TDI Air Diluent Closed Circuit Rebreather Diver Course for the Discovery Poseidon MkVI/SE7EN CCR is the entry level certification course for divers wishing to learn about or purchase the Poseidon Mk6 Rebreather. The objective of the course is to train divers in the benefits, hazards and proper procedures for diving a Discovery Poseidon Mk6/SE7EN CCR and to develop basic diving skills to a maximum of 30 metres / 100 feet using air as a diluent. No decompression diving is allowed on this course.

Divers need to be Nitrox qualified, however this can be included as part of the course (see below).  Divers already qualified as TDI Advanced Nitrox & Decompression Procedure Divers, or equivalent) are able to jump right in to the TDI Air Diluent Decompression Procedures Course for the Discovery Mk6/SE7EN CCR.

The Poseidon Discovery is the world’s first rebreather for recreational divers. It’s a fully-closed, fully-automated unit that will make you see diving in a different light.  The system comprises a breathing loop (mouthpiece, hoses and counter lungs) with associated electronics module, and two independent gas cylinders. One contains 100% compressed oxygen which is added to the breathing loop as the diver consumes it. The second cylinder typically contains compressed air “diluent” to compensate for compression in the breathing loop as the diver goes deeper. It’s also a back-up system, containing enough oxygen for the diver to breathe directly in an emergency.

The dive is fully managed by on-board computers, with two continuously recalibrating sensors constantly monitoring oxygen levels, and dive information recorded in the removable battery module. The hand-held control unit displays depth, cylinder pressure, and oxygen concentration. The system is also equipped with a number of active warning systems.

To begin the dive, the diver must ensure that the battery is charged, the bottles are filled with gas and the pre-packaged scrubber is attached. The computer then performs a thorough pre-dive test to ensure that all parts of the system are functioning properly before the dive is allowed to proceed.

Light, safe and simple to use, the Discovery is designed not only for seasoned divers, but for those who are new to the experience. With so much less to do, you’re free to concentrate on the dive itself. And with no bubbles to frighten the sea life, it’s a dive you’ll enjoy more than ever. It’s also a dive you can enjoy for longer, with the potential to stay under water for up to three hours at a maximum depth of 40 m.

At just 18 kilos (39.6 lbs) fully gassed up and ready to dive, the Discovery MkVI/SE7EN weighs less than many dive tanks weigh on their own. And minus tanks and canister, it weighs just 8 kilos (17.6 lbs), making it easy to travel with.

Poseidon Discovery Mk VI/SE7EN CCR Course – Cost

  • TDI Air Diluent Diver Poseidon MkVI/SE7EN (30m) – $1895 (includes online training)
  • TDI Discovery MkVI Rebreather for hire for course – $450 (does not include consumables)
  • SDI Nitrox Program  (if not Nitrox Certified)- $225

Course dates: We do them to suit your schedule, just ring John on 9958 5699 to arrange dates

Try dives available no charge at our Willoughby Scuba Centre at 6:00pm

2019 Dates

All try dives are starting at 6pm

March 13th, May 15th, July 17th, September 11th






Download the Poseidon 7 course application form here.

Student Dive Equipment

You will need:

  • Complete Discovery Mk6 Rebreather (available for hire)
  • Mask, snorkel, fins and boots
  • Appropriate insulation
  • 1 bottom timer / Dive Computer
  • 1 torch
  • Knife
  • Whistle
  • Surface Marker Buoy and Reel
  • Pony Bottle/Bailout Cylinder & Regulator (available for hire).

Knowledge Development

  • History and Evolution of Rebreathers
  • Comparison and benefits to Open Circuit, SCR & CCR diving
  • Practical Mechanics of a Rebreather
  • Gas Physiology
  • Scrubber Packing
  • Electronic and Manual Features – Design and Maintenance
  • Dive Tables
  • Dive Planning
  • Emergency Procedures
  • Automatic Pre-Dive Test

Course duration

  • Air Diluent 30m Course – Pool and at least 7 Open Water dives over no less than 5 days.
  • Air Deco Diluent 45m Course – Pool and at least 7 dives over 5 days.

Course includes

  • All training packs
  • All Shore dives and Boat Dives
  • Certification through TDI when course training objectives are successfully achieved.