Mount Vesuvius is an amazing experience and must see if you’re in Sorrento!
You take the train to Pompei, then take a bus to the bottom of Mt. Vesuvius – THEN you take a “super” bus up the mountain (very bumpy and a bit scary- be wary if you get motion/car sick) and then get dropped off 2-3km below the top.
The hike is a HIKE but it is worth it. The views are incredible- you can literally see the entire city below!