Allison and Carter's engagement hits rough waters when Carter's attempt at romance traps them at the bottom of Lake Archimedes in a leaking sub. Their survival depends on Jo's ability to sort through a series of pranks at GD, Eureka style, and an experiment gone terribly wrong.

original airdate-- June 11,2012                      rating--1.45 million

song--Eureka Theme song--"Eureka On My Mind" by Bear McCreary