Riverboat travel was hazardous. From 1811 to 1851, 21% of river accidents were caused by a steam explosion. Boilers built pressure to power paddleboats. If these tanks were not adequately monitored or maintained, the result could be a violent and deadly explosion. Another danger of river travel was a ‘snag.’ A snag is an unforeseen obstacle that damages or causes a boat to sink. Snags might include sunken boats or trees. It was rare for a steamboat to last five years.