Little Blue Lake facts for kids

The Little Blue Lake is a special water-filled hole in the ground called a sinkhole. It's located in South Australia, near a place called Mount Schank. This spot is about 20 kilometers south of Mount Gambier.

People love the Little Blue Lake for swimming. It's also a famous place for cave diving in Australia. The local council looks after it, making it a fun spot for visitors and locals.

Why is it Called Little Blue Lake?

This sinkhole got its name because it looks a bit like the much bigger Blue Lake in Mount Gambier. Sometimes, its water even turns blue in the summer.

However, these days, the water often stays green most of the year. Some people think this is because of groundwater pollution. Water from nearby farms might carry extra nutrients from fertilizers into the lake.

The lake also has other names. Some call it Baby Blue. In books about caving, it's known by a special code: 5L9.

What Does Little Blue Lake Look Like?

The Little Blue Lake is about 20 kilometers south of Mount Gambier. You can find it near Mount Salt Road, not far from the main road called the Riddoch Highway.

The lake itself is about 50 meters wide. It has tall cliffs around it, reaching about 9 meters high. To get to the water, there's a special path cut into the side. This path leads to a metal staircase and a small floating platform.

The bottom of the lake is mostly flat and silty. It's usually about 36 meters deep. The shallowest part is around 25 meters deep, right under the access ramp. The deepest part can be over 42 meters, depending on how much water is in the ground.

The water isn't always clear, but sometimes it gets better the deeper you go. Over the years, some interesting things have ended up at the bottom of the lake. Divers have found an old car, a petrol pump, and even traffic signs!

How Little Blue Lake Formed

The Little Blue Lake is one of many sinkholes in this area. They are all found in a flat coastal plain made of a type of rock called Gambier Limestone. These sinkholes are like giant holes that formed when underground caves collapsed.

Scientists believe these caves were created a long time ago. Water, made slightly acidic by gases from volcanic eruptions, dissolved the limestone. Then, about 20,000 years ago, sea levels dropped. This might have caused the large underground chambers to collapse.

Later, as sea levels rose again about 8,000 years ago, the sinkholes filled with fresh water. The presence of special rock formations called stromatolites in the lake suggests these landforms are quite new.

Exploring the Depths

People started exploring the underwater parts of the Little Blue Lake in the 1950s. Divers have mapped out the lake's hidden areas. The Cave Divers Association of Australia (CDAA) also surveyed it in the 1990s.

Little Blue Lake Today

Today, the Little Blue Lake is a very popular spot. Many people come here to swim, especially during warmer months.

The land around the sinkhole was made a public park in 1986. The local council has worked to make it safer and more enjoyable. In 2002, they added the stairs and the floating platform. There's also a parking area nearby.

If you want to dive in the sinkhole, you need to be a trained cave diver. Only divers with a special certification, like the CDAA Deep Cavern grade, are allowed to explore its depths.

See also

• List of sinkholes of Australia
• Ice age