Australian Geographic - 09.2019 - 10.2019

46 Australian Geographic

AG

On the fourth day, we’d haul our gear back up 250m of ropes to

the surface and navigate our way back through the series of

squeezes in the cave’s upper sections. One particular section, the

500m-long Tigertooth Passage, was so narrow we would need

to walk sideways, with protruding rocks likely to snag loose straps

and gear with frustrating regularity.

T

HE DIVE DIDN’T begin well. It was 8.45pm before we

were set up at the Pool of Promise and I was ready to

jump in. I started pushing through the tunnel, reached

a dead end almost immediately, backtracked through my own

silt cloud and managed to find and follow the left wall. I made

good progress before the wall pinched away. Ahead of me was

a horizontal slot – between the silty f loor and the rock ceiling

above there was a gap of only about 25cm. It was my best option

for forward progress.

I’d been securing my guideline as I made my way through

the cave, but this section was a classic cave diver’s ‘line trap’ –

where the guideline could easily get dragged sideways into the

impossibly low passage. If this happened, I could get into trouble

when following the guideline on my return. I pegged it to the

f loor with silt pegs and was progressing forward, lying f lat

between the f loor and ceiling with my head tilted sideways

because there wasn’t enough room for me to keep it upright.

Clouds of silt obscured my vision, but I was moving forward

through the water, when my reel of guideline ran out. I fumbled

blindly with thick gloves to switch reels and then charged ahead,

surfacing quickly in a large, dry chamber. I made a solid tie-off

on a rock protrusion above the water and added an arrow as a

reminder of the way out.

At the far end of the chamber was a small cobble beach, and

just beyond, a tiny pool with barely enough room for me to put

my fins back on, but while the passage forward was low, it quickly

opened up into a large underwater cave.

I knew I was close when my second reel of guideline ran out

• we’d calculated the distance to the connection point would be
  about 220m. After 200m, my uncertainty was growing. Then
  I saw the guideline I’d tied off years earlier. Here, finally was
  the connection many cavers thought would never happen.
  By combining the lowest point in Growling Swallet with the
  highest point in Niggly Cave, we established that this cave system
  is 397.7m deep, a new depth record for an Australian cave.
  Niggly Cave and Growling Swallet have plenty of secrets left
  to discover. This summer we may attempt a complete through-
  t r ip f rom one cave to the other. If not, we’ l l def in itely be back.

Thermal protection

Drysuit (to keep

the diver’s body

completely dry)

Layers of warm

undergarments

7mm-thick neoprene

hood (to keep the

diver’s head warm)

Heated wetsuit

gloves

Recording equipment

Surveying gear

(compass, wrist

notes and dive

computer with

depth gauge)

Helmet-mounted

camera

Knotted guideline

(for measuring

distances)

Diving equipment

Lightweight

composite cylinders

(two cylinders hold

enough breathing

gas to fill 1500

balloons)

Nitrox (nitrogen-

oxygen gas mixture)

Reels of guideline

Silt pegs (for securing

guideline)

Helmet with

mounted lights

Spare lights

Spare diving mask

Gearing up

Exploratory cave diving requires extensive

training and experience, as well as some

special equipment to ensure diver safety and

maximise the chance of success.

All our equipment

is carefully selected.

Every piece must be

able to be carried,

dragged through

squeezes, lifted up

ropes, dropped on

rocks, covered in mud,

submerged and/or

potentially left in the

damp environment of

the cave for what could

be years at a time.

WATCH To see footage from this expedition and from a

documentary that’s in production, head to tartarusfilm.com