#OTD #TDIH #April5, 1958: #RippleRock, an underwater threat to navigation in the Seymour Narrows in #BritishColumbia #Canada, is destroyed in one of the largest non-nuclear controlled explosions of the time. #RippleRockExplosion #NationalHistoricEventsOfCanada #LargestNonNuclearExplosions #TVSky