I can see how it might be that way, but Morrison is a /really/ stable place. No boat traffic, plenty of open space, lots of places to sit and sort your gear out (platforms, logs), and a simple entry via shore with no current or steep grades. The only strong current is at the cavern entry, but its still highly puny.
The riskiest part of a dive, even a ‘penetration’ dive into a cavern, is the drive in your car to the site. 
