Complex sentence: The Mariel Boatlift, was a series boatlifts that took place from the 15th of April to the 31st of October 1980 which brought 125,000 Cubans from the port of Mariel to southern Florida.
Split into simpler sentences: The Mariel Boatlift, was a series boatlifts that took place from the 15th of April to the 31st of October 1980. The boatlift was responsible for the transport of 125,000 Cubans from the port of Mariel to southern Florida.