It is illegal...

• To operate a watercraft in a reckless, negligent, or dangerous manner. Boats must be operated at a rate of speed that does not endanger the life or property of any person.
• To operate a boat at greater than slow, no-wake speed within 100 feet of the shoreline, docks, launch ramps, swimmers or downed skiers, persons wading in the water, anchored, moored or drifting boats and floats. Slow, no-wake speed is the slowest possible speed of a motorboat required to maintain maneuverability so that the wake or wash created by the motorboat on the surface is minimal.
• To operate a motorboat less than 20 feet in length at greater than slow no-wake while a person is standing on or in the boat.
• To operate a motorboat not equipped with railings or other safeguards at greater than slow, no-wake while a person is riding on the bow decking, gunwales, transom, or motor covers.
• To cause a boat to become airborne or to leave the water completely while crossing another boat’s wake when within 100 feet of the boat creating the wake.
• To weave through congested traffic.
• To operate faster than slow, no-wake when within 100 feet to the rear or 50 feet to the side of another boat that is underway, unless in a narrow channel.
• To operate within 100 feet of anyone towed behind another boat.
• To operate a pontoon boat at greater than slow, no-wake speed while a person is riding outside the passenger-carrying area.
• To operate within 100 yards of any U.S. Navy vessel. You must operate at slow, no-wake speed within 500 yards of any U.S. Navy vessel.
• To operate a motorboat which anyone sitting, riding or hanging on a swim platform or swim ladder attached to the boat.

Many waterways in Pennsylvania have special regulations such as horsepower restrictions.