Complex sentence: This was the sixth vessel to be named HMS "Discovery" and the first recorded the sighting of Mount St. Helens by Europeans was by George Vancouver on May 19,1792, while they were surveying the northern Pacific Ocean.
Split into simpler sentences: This was the sixth vessel to be named HMS "Discovery". The first recorded sighting of Mount St. Helens by Europeans was by George Vancouver on May 19,1792, while they were surveying the northern Pacific Ocean.