With a sheer vertical drop of 106m (and a second drop of 30m), Boka is the highest waterfall in Slovenia – and it's especially stunning in the spring, when snowmelt gives it extra oomph. It's 5.5km southwest of Bovec – you can drive or cycle to the area and park by the bridge, then walk about 15 minutes to the viewpoint.
Alternatively, take a walk from town: follow the relatively easy B2 marked path via the village of Plužna and the Virje waterfall, or the more difficult S1 on the Bovec z Okolico (Bovec and Surrounds) map.