Exceptionally low water levels on some of Europe’s most iconic rivers are having a dramatic impact on river cruises. Viking, for example, has the largest river cruise ship fleet in the industry and is continually monitoring river conditions. Similar to hurricane storm changes, it is possible that river cruise changes will be made at the last minute. This is often the first stretch of the river that will show problems that could impact river cruise ships. Because the Danube River stretches from Germany to Romania, there can be great variation in depth along its 1,770-mile length.