In OMSI lot. You have to go into OMSI main entrance and check in before you go down to the submarine
They have handicapped parking upfront if that is an option for you. Other than that you can possibly drop them off close to the front entrance and then go park. About 40 feet or so to the entrance to OMSI. From there it's a decent walk to the submarine. Might want to bring a wheelchair or 4 wheel walker to assist them. Good luck and enjoy!
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