If I buy a Combo Ticket, do I have to visit SEA LIFE on the same day?

No! The timeslot you select to visit is your arrival time to LEGOLAND Discovery Center San Antonio. You're welcome to visit SEA LIFE any time within the next 30 days. The average family spends 60-90 minutes at SEA LIFE and 2-3 hours at LEGOLAND Discovery Center. Please see each attraction's website for complete hours of operation.