I think you are enquiring about the underground cave systems. Either those of Waitomo in the North Island, or those of Te Anau Au of Lake Te Anau in the South Island. Both have well developed tourist industries.
Magma Collects Deep Underground in areas known as Magma Chambers i hope this answers your question.
The reason seawater is trapped in huge shallow pools in stead of small deep ones is beacause huge shallow pools has a larger surface area, allowing the water to evaporate quicker leaving the salt behiend.
The pools may or may not be deep as "deep" is a relative term here. Use the link below to get some contact information and make a direct inquiry.
How deep is wipeout water
150 feet deep. you will this on the travel channel. it comes on rarely so check it everyday.
Most swimming pools are between 4 and 10 feet deep. The World's Deepest Pool, though is 108 feet deep.
4.5 FT
Not that deep, because they live in pools
False, the focus is located deep underground. The epicenter is at ground level
Some pools have a shallow end to warm up in, and then the playing area is deep, some have just deep water, some are half and half. I depends on what pool you are in.
2.0 meters
9feet