What is a lake?
A lake is a body of water surrounded on all sides by land. Lake water is still or standing, meaning it doesn't flow to point A to point B in the same way a river does, and since they are often fed by rivers they are primarily freshwater.
Lake Taupo
Lake Taupo was made was created approximately 27,000 years ago by a huge volcanic eruption and according to geological records, it erupted over 28 times in the last 30,000 years. Water filled the volcano because plenty of earthquakes were caused by the volcano. through resources of water or rain fills the caldera which is the top of the volcano.
Fig 2 and 3
Images of Lake Taupo from a cool prospective