The Segnesboden wasserfall is one of the taller waterfalls in Switzerland and is located north west of Flims in the region Graubünden.
From Chur it is only a 20 minute drive to Flims over road E43>19. In wintertime Flims is a popular skiing area but in summertime popular for hiking.
From the centre of Flims it is a three hour walk to the Segnesboden wasserfall, with an ascent of approximately a thousand meter. There is a special route called Trutg dil Flem or Flimser Wasserweg that runs along the river Flem. A map and more information can be found here.
If you want to take it easier you also can take the cable car up to berghaus Naraus form Flims. The ascend is then a lot less for the hike to the Segnesboden wasserfall. And the walk take 1-1,5 hour instead of three hours! But still an ascend of 260 meter.
I am not sure if it is possible to drive to the cable car at Grauberg, but this lift is also open in summertime. It is possible to take the cable car up to Foppa, walk to the Grauberg lift and there go up again. From Grauberg it is only a 30 minute walk to the Segnesboden wasserfall.
The Segnesboden wasserfall is located on an altitude over a 2000 meter, which is quite special. There aren’t that many waterfalls in such an high altitude in Europe.