What should we do in Nau for a few hours?

We are on a Canival cruise that ports in downtown Nau for 10 hours. I'm sure we'll do an excursion for a couple hours, but that still leaves a lot of time in port. I hear there are bike rentals near the port, so I'm wondering what is a must-see in Nau if we're cruising around on bikes or a scooter? Any local restaurants that we have to try?