Consequences of boating under the influence in illinois?

Other answer:

Same as Driving Under the Influence (DUI). They'll impound the boat, revoke your boating license, and probably revoke your driver's license too. Fines, possible jail.
The first and most serious result is the same in any area of the world,—- death by drowning.
The second is as Josh and Ian have said.
Ian K:
Besides killing someone else, or yourself, arrest, jail, fines, loss of boat, etc.