There are 7 buses daily (5 on weekends) from Barcelona via two different routes (Amer or Banyoles), time travel 2 hr 30 min. Connections are more frequent from Girona, which run hourly on weekdays with some direct buses in just 1 hr travel time, others 1 hr 30 min. From Girona do NOT use the buses via Amer, they're way slower, about 2 hr 15 min!
By car, if coming from Barcelona the best route is using the C-17 autoroute up to Torelló and then diverting thru Bracons tunnel. From Girona, head towards Banyoles, then Besalú and finally Olot. As with the bus, avoid going via Anglès and Amer. From France, at Figueres head towards Besalú.
Finally, there's a cycling route all the way from Olot to Girona following the path of an ancient narrow gauge railway. It closely follows the Amer route.
Santa Margarida VolcanoWith a chapel inside this is one of the volcanoes of the Garrotxa Volcanic Zone Natural Park, a natural park on a extinct Holocene volcanic field.
La Fageda d'en JordàFagus sylvatica forest natural park.
Espai museístic del Volcà del CroscatAt the Croscat volcano a huge part has been cut out (accidental or intentionally) which allows you to take a look inside of a volcano. Basically a huge and steep quary made of volcano sand/rocks. But it is impressive and huge.
Garrotxa Volcanic Zone Natural Park.