The Dive Otter

Pony Bottles

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What is a "Pony Bottle"?

Lots of different names for the same physical thing, a tank of breathable gas with an isolated/separate regulator. But based on the name, it typically means something different. And is usually...

Smaller tank than primary tank but filled with the same gasFull sized tank filled with the same gasFull sized tank filled with a specific gas intended for a specific depth
  • - Pony Bottle
  • - Bailout Bottle
  • - Redundant Air
  • - Emergency Gas Supply
  • - Bailout Bottle
  • - Stage Tank
  • - Deco Bottle
Recreational Diving Technical Diving
Not Included In Gas Planning Included in Gas Planning

How is a Pony Bottle typically carried? everything in scuba...there is no "typical" way of doing something. There are several different methods:

Picture from NW Dive Dawg at Scubaboard

Attached to Backmounted Tank

  • - It's out of the way
  • - It's out of the way
  • - Need to move it between tanks on a "two tank" dive day
  • - Can't hand it to a buddy
Picture from matthewoutram at

Side Mount / Side Slung

  • - Easy to don/doff
  • - Can see it if you need to during the dive
  • - Easy to get to during the dive
  • - Easy to "hand off" if your buddy needs it
  • - Requires Shoulder and Hip DRings
  • - Clutters up the side/front of the diver

How is a Pony Bottle typically setup?

With the exception of the attachment to the diver (back or side) the setup is generally the same.
You need:
  • - (1) Tank
  • - (1) 1st Stage Regulator
  • - (1) 2nd Stage Regulator (typically no octo/safe second)
  • - (1) Hose of an appropriate length
  • - (1) SPG (typically on a short hose of ~6 inches) Has a set of great articles on Deco/Stage Bottle Rigging

UTD has a cool SPG Rigging Tip when side slinging.
What a side slung Pony Bottle might look like
Image from

How big of a tank should I have?

I don't know....what's your dive plan? Why not use the Rock Bottom Gas we already calculated for this dive as the maximum we would need? Using the example of a 100ft dive with an RMV of 0.75 and two divers on the same bottle surfacing at 10ft per minute, we can calculate how much gas we need...
...~40cft of gas. Which means if we sling a 40cft bottle that will be plenty, because we are not planning for full catastrophic air failure on all primary gas across both you and your buddy. This should be for one diver...and we will have enough for two. Excellent. Note: Generally speaking, for a recreational diver, a 40cft pony bottle is the optimal choice in the Great Lakes region if you only want to own one Pony Bottle. Some divers will drop to 19cft because it is half the size and thus easier to manage, however they are cutting their margin of error in half. I personally want more conservatism in my risk calculation.

How much does a Pony Bottle cost?

40cft Tank$250Many divers will go with a yellow color. However, there is nothing wrong with a plain aluminum one. Typically, divers do not use steel pony bottles, even when diving a drysuit, because of the buoyancy characteristic of aluminum at this size is essentially immaterial. (-1.5lb full / +0.7 "empty")
1st Stage Regulator$300You can certainly go cheaper. But this is literally your last ditch option for air at 100ft (in our example)...I want a great regulator that is bulletproof and freeze resistant (in the great lakes)
2nd Stage Regulator$300See above...I want a regulator that is as good as my primary.
SPG \w 6" hose$150Get one that is easy to read and not too small
Stage Bottle Rigging Kit$70Lots of different brands make them. Hollis, DiveRight, Halcyon...just pick one