What is associated with: columbus native buster douglas was a 1990s champion in this sport dubbed the sweet science?

Based on the clue 'columbus made his fourth final voyage to the new ...', what is the answer? What is associated with: columbus may have spotted the mouth of this venezuelan river in 1498? Based on the clue 'columbus named the island now usually called st ki...', what is the answer? Based on the clue 'columbus named this flagship on his 2nd voyage aft...', what is the answer? Based on the clue 'columbus ohios main drag is called this more often...', what is the answer? Based on the clue 'columbus personal flag bore the initials f y whic...', what is the answer? What is referred to by 'columbus philadelphia hartford'? Based on the clue 'columbus reaches south america for the first time', what is the answer?