Sam Houston boat tour – how to get there from downtown?

Is the best way to get to the boat tour by uber? I’m visiting and staying downtown, don’t drive, and saw that there is a public bus from my hotel directly to outside of the port. But once I’m there, will I be able to walk in through the security gates or must it be a vehicle entering? I’ve tried to email them but no response. Hoping someone here has insight. Thanks!