Sailing Lake Garda: what dangers?

The map below shows the dangerous zones that one can encounter sailing on Lake Garda: outcropping or dry rocks.

Sailing general rules

Maximum speed: 20 knots during the day and 5 knots during the night.
Waterskiing: from 8.00 a.m to 8 p.m maximum speed 25 knots, al least at 500 m off the shore
Diving: divers starting from the shore shall highlight their presence with a marker buoy bearing a red flag with a diagonal white stripe, otherwise they shall be followed by a support unit. Boats shallkeep at a distance of atleast 100 m from the buoy.

Yellow Zone: Powerboat navigation is forbidden within 300 m from the shore: it is allowed to near perpendicular to the coast at a maximum speed of 3 Knots.
Red Zone: Gulf of Salò and Romantica, between the mouth of stream Barbarano and Rocca di Manerba, around the Isle of Garda and at the end of promontory Sirmione – Punta Grotte: Powerboat navigation is forbidden within 150 m from the shore: it is allowed to near perpendicular to the coast at a maximum speed of 3 Knots
Green Zone: In the waters falling within the competence of Trento autonomous Province power boat navigation is forbidden. Sailing crafts may use engines to leave and access the marinas or to sail back to the marina in case of lack of wind or for other justified reasons