There are multiple ways to see the Apostle Islands Sea Caves! In addition to paddling them, you can hike above them (https://www.alltrails.com/trail/us/wisconsin/meyers-beach-sea-cave-trail) or take a multi-way trip out into the islands!
Hike and swim in Siskiwit Falls by Cornucopia.
The Siskiwit Lodge has a nice list of ideas, which can be found here.