According to the National Parks website, Bool Lagoon is a large seasonal freshwater wetland with a wide range of wildlife including rare and endangered bird species. Unfortunately, when we visited about a month ago, the main basin of the lagoon didn't seem to have any water. Nonetheless, we took a drive around and walked the Tea Tree Boardwalk trail.
The trail was easy enough to be completed within half an hour. It has a gentle gradient, with mostly flat timber planks, and extends approximately 500 metres to a bird hide. I enjoyed the surrounding scenery, but it might have been better if the water was flowing. We saw a few birds and could hear the frogs when we stopped to listen.
Driving on, we arrived at the adjoining Hacks Lagoon which surprisingly had plenty of water! The Pat-om walking trail will lead you closer to the inlet channel while, on the other side, an area known as Hacks Island can be explored. Here, we also saw water passing through the Gunawar channels under the pontoon.
As for facilities, there's only a carpark at the trailhead. Toilets and a small picnic area can be found in the nearby campground. Both the lagoons are accessible via Bool Lagoon Road, just off Riddoch Highway, near Naracoorte. Entry is free.