Spend the day in Miami, what can I do with my luggage?

In April I'll be returning from a cruise early in the morning. Considering spending the whole day checking out Miami, going to the beach, going out to dinner before heading to the airport. My question is, does anyone have suggestions of what to do with my luggage during this time? I'm wondering if maybe a hotel would hold my luggage for a fee, even if I'm not staying there. Any other ideas?

See if your cruise line (by asking on the cruise line board here) if they have a luggage program, where you leave your bags outside your room the last night, and don't see them until your home airport.

Or rent a car, put them in the trunk.

Agree with CruiserBruce. Rent a car and you can leave your luggage in the trunk.

"Luggage Lounge" in South Beach will store your bags for a fee, leaving you free to explore, beach, lunch, etc. You can also try www.resortpass.com for larger hotels and resorts that will sell you a day pass for their pool, spa, beach and other facilities -- tip them to hold your bags.

You can also pay to store your bags at MIA - from their hop the Miami Flyer Bus (about $3) to downtown/South Beach for the day and then bus or Uber back to MIA.

Luggage Lounge South Beach.

We went to the airport, checked our luggage and took the shuttle to South Beach. The only issue, our luggage got home 6 hours before we did. :)

Most airlines will not allow you to check your bags earlier than 3-4 hours prior to your scheduled departure. There is luggage storage available at MIA for a fee.