There are plenty of great synonyms for the phrase "seize the opportunity." Some of these alternatives include "grab the chance," "seize the moment," "take advantage of the situation," "make the most of the opportunity," "capitalize on the opening," and "jump at the possibility." These phrases all convey the same idea that if an opportunity presents itself, it is important to act quickly and take advantage of it before it is gone. By using some of these alternate phrases in your writing or speaking, you can add variety and interest to your language while still conveying the same essential meaning.