Complex sentence: These nautical parades, witnessed by several million observers, were named Operation Sail (Op Sail), and this was the second of five such Op Sail events to date (1964,1976,1986,1992 and 2000).
Split into simpler sentences: These nautical parades, were named Operation Sail (Op Sail) and witnessed by several million observers. The gathering was the second of five such Op Sail events to date (1964,1976,1986,1992 and 2000).