Buoyancy experiment prompted Waiakea lockdown


A Cartesian diver science experiment that a student inadvertently left from a previous period prompted today’s lockdown of Waiakea High School, school officials said.

The school went into lockdown at 11:48 a.m. after a suspicious object was discovered at the school, according to police. First responders arrived shortly thereafter, including members of the Hawaii County Police and Fire departments. The lockdown was lifted at 12:24 p.m. No injuries were reported.

In a prepared statement, Waiakea High School Principal Kelcy Koga described the object as a water bottle with a piece of metal inside it. That fits the description of a “bottle bomb” that was set off at Hilo High School just over a month ago. No one was injured in that instance, but two students were arrested in connection with the disturbance, which locked down the school for more than an hour.

“The device was found by a custodian around 11:45 a.m. on a grassy area in the center of the campus, and it was a bottle with water and what looked like metal inside,” Koga said. “A lockdown was initiated for precautionary reasons. Police were called to the campus, and they removed the object, that was identified as a Cartesian diver science experiment a student had inadvertently left from a previous period.”

The Cartesian diver is a classic science experiment attributed to Rene Descartes which demonstrates the principle of buoyancy, using a small tube floating inside a container filled with water. When the bottle is squeezed, the tube dives to the bottom of the container because of the change in pressure.