As a person with a multi-ethnic background who has traveled extensively, BU's diversity is very important to my college experience.
.... I think you better start with this sentence. Since you have a tough word count, you can even remove the first sentence and include something more meaningful and relevant to your response.
Furthermore, BU's active student body ensures me that with my interest in soccer, the environment and much more, I will continue to thrive in the high-performing atmosphere of Boston University.
... the ideas are pretty cramped in this sentence. If you save some words by eliminating the first sentence, you can expand a bit on this idea. This gives more important information than the first one.