First, a disclaimer - I haven’t been to Cozumel in March in a little over a decade - 2007 was the last time - so my information may be out of date. BUT, for many years up to that time I came to Cozumel the last week in March every year. Yes, there was a SLIGHT increase in the number of Spring Breakers in Cozumel, but nothing anywhere close to Cancun or Playa Del Carmen. And if you avoided Carlos & Charlies, Senor Frogs, and Margarittaville, you had a good chance of missing them altogether. Now I was always on a dive boat during the day, so I can’t say what the Spring Breakers were doing during the day - I suppose it is possible that they invaded one or more of the Beach Clubs. But I very much doubt that you’ll see more than a smattering of Spring Breakers unless you take the Ferry over to PDC.