Seven young men disappeared on Lake Ontario after St. Patrick's Day Shenanigans. 

Sources:

The Star "20 Years Later, the Lost Boys Mystery Remains." Kristen Calis March 20, 2015
DurhamRegion.com "The Mystery of the Lost Boys" Three-Part Series Kristen Callis April 12, 2018, April 18, 2018, April 26, 2018
DurhamRegion.com "DNA Testing Yields No New Clues to Fate of Pickering's Lost Boys" Jeff Mitchell December 24, 2018