Say "tiger shark" and most people would try get as far away as possible.
Not so with the scientists from the University of Hawaii Institute of Marine Biology who search out the tigers to learn more.
One of these scientists Carl Meyer, has been tagging tiger sharks for decades.
Thanks to surgically implanted acoustic devices, scientists have collected years of valuable data about shark migration patterns.
And they're complex:
A tiger spotted in Oahu waters in the morning can be in Molokai in the afternoon.
Special receivers set up across the Hawaiian chain have also picked up signals of tagged great white sharks that come from as far away as California.
"What we have seen with the white sharks is they tend to be in relatively deep water. So unlike the tiger sharks which are routinely in shallow water, we almost never hear the white sharks in less than 100 feet," said shark expert Carl Meyer.
There are smartphone apps like Expedition Great White that trace the movement of great white sharks in real time.
Meyer says Hawaii scientists are considering something similar.