The Krupa itself is a small river which joins the Vrbas in the canyon. Krupa spreads itself out along the Krupa, and by the main road Jajce-Banja Luka.
The town is known for the "Krupa falls", the waterfalls in the town. Indeed the crystal clear waters racing down between the traditional watermill make a lovely sight. By the waterfalls you can even buy freshly ground wheat, or eat some trout at the trout farms just below.
After the waterfalls you can take a quick tour by the monastery - which is basically a church and a very new building where some priests live - an hike up to 'Greben', the old watchtowers, where you have a very scary and spectacular view over the Vrbas canyon and the town.
Also a hike to the source of the Krupa is not too challenging and always appreciated.
In Krupa, behind the school, towards the Vrbas, is Kamp Krupa, run by the Kanjon rafting club  where in the summer is a camp-site.
When you're into rockclimbing, you can also go a few km north down the Vrbas, cross the river at the hanging bridge to climb up the stone bridge ('kameni most'), but you need to arrange you own climbing gear or contact Julien.
If you come from direction of Sarajevo, choose a bus coming through Travnik and Jajce. This bus will continue to Krupa before arriving in Banjaluka. Do not take the bus which goes over Doboj, as it will not pass Krupa.
It is unclear if at the bus station of Sarajevo you can buy tickets for Krupa, so if not, get a ticket for Banja Luka instead. Remember to make sure the bus doesn't goes over Doboj. Ask the driver to let you out in Krupa. Krupa comes 25 km after Jajce, the town with the big waterfall.
If you come from Zagreb, take the bus to Banja Luka.
When you arrive in Banja Luka, you change to the bus to Krupa. This bus is a local line and it is operated by BOČAC tours. Take either the bus to "Krupa n/V - BOČAC" or "AGINO SELO". These buses leave from the departure place of the city buses, which is different then the intercity bus station where you would arrive. It is left of the trainstation ("Zeljeznicka Stanica"), which is 200 meters from where you arrive in main bus station.
The ride costs 3,5 KM (Konvertibilni Maraka, ~€1,75) and takes about 40 minutes. The bus goes straight to the center of Banja Luka, so there is also the possibility to catch it in the center; for example from the "old bus station", behind the museum of contemporary arts.