Lake Disappear

Lake Disappear is in the valley of Pakihi Stream. This valley was dammed by a basalt lava flow in the Early Quaternary, about 2 million years ago. Kawhia Rd runs along on top of this flow which forms a natural dam. At the eastern side of the lava flow the stream flows into a limestone sinkhole and flows underground for about 2 km before re-emerging and flowing down into Aotea Harbour. After the lava flow was emplaced, the stream found a new route through an underground cave. After heavy rain the cave system is not large enough to carry all the water and a lake forms extending for 2 km or more back up the valley. In dryer weather the lake drains away completely.

If you stop and look up the valley, is the lake present or absent during your visit?
How do you think the underground cave through limestone was formed?
Across the road just west of some farm buildings there is a large funnel shaped hole in the ground - how do you think it formed and why is it not full of water?