Goulden's Hole is the workhorse of Mount Gambier's cave-training scene. It is a smaller sinkhole than Kilsby's or Little Blue, managed by DEW, and the CDAA describes it simply: some yabbies and fish, thermoclines at 15 m, visibility usually good, often used for training and courses. Most CDAA Basic Cave divers in Australia will have done at least one course dive here.

The layout is a compact open bowl with walls dropping from the grassy rim to a floor in the mid-20-metre range, with the daylight zone covering the whole sinkhole. That makes it ideal for practising guideline work, gas-sharing and light signals in a setting with a real ceiling of water but no rock overhead. The thermocline at about 15 m is distinct – the water above can be greener and slightly warmer, and below it the visibility usually opens up. Yabbies wander the ledges and small native fish hang around the shallows and weed.

Booking is formal: DEW caps numbers at 12 divers per timeslot including instructors, requires a minimum of two divers diving together, 48 hours' notice and a signed indemnity, and limits each diver to two slots per day. On course weekends it can therefore be busy, and instructors tend to run skills circuits on the floor while pleasure divers drift the walls. It is not a site you travel across the country to see, but it is a reliable, predictable place to learn, refresh skills or shake down new gear. It suits CDAA Basic Cave divers, trainees and anyone setting up for the more serious sites nearby.

Goulden's is managed by the Department for Environment and Water and booked through parks.sa.gov.au (listed under Piccaninnie Ponds Conservation Park). Book at least 48 hours ahead, submit a signed indemnity and have your CDAA qualification verified; confirmation includes directions and access details. The site lies in the Mount Schank area, about 15-20 minutes' drive south of Mount Gambier on the Riddoch Highway side roads.

Park where directed and carry gear the short distance to the water's edge.

Sheltered and unaffected by swell. Two DEW timeslots daily (6 am-noon, noon-8 pm), so plan around slot limits rather than weather. A thermocline at about 15 m changes clarity and temperature; summer algae can reduce shallow visibility.

Heavy rain may muddy the access path. Check DEW for low-water closures before driving out.

Enter from the edge, descend the wall to the thermocline at about 15 m, then circle the sinkhole within the daylight zone at 15-25 m. Training teams typically run skills (line laying, lights-out, gas sharing) on the floor in the open area before ascending the wall to a stop in the shallows.

CDAA grade: Basic Cave (5L8), owner DEW. Book via parks.sa.gov.au (Piccaninnie Ponds CP listing) ≥48 h ahead; two slots daily (06:00-12:00, 12:00-20:00); max 12 divers per slot; min 2 per booking; max 2 slots per day; indemnity per diver. No overhead; stay in daylight zone.

Used heavily for CDAA Basic Cave courses (Diving Adelaide, Deep Blue Ventures, CDAA instructors) and by CDAA members on DEW bookings; no Open Water tours.