One of the options is a one-day 220km ride, that takes in 7000m of climbing and decending. The dropout rate can be as high as 70%. Frankly, this makes the UK's enduros look like a walk in the park, so it's no wonder the attrition rate is so high...
If that sounds too much like hard work, there are also easier 100km and 47km options (but even these leave you with 2900m and 1750m changes in altitude to contend with.) The 100km race is a qualifier for the UCI Marathon series.
For more info on this event, go to: this site
General regional info at: http://www.salzkammergut.at