An ultrasonic humidifier includes a tank having a water level and a floater having a tubular structure with a bottom rim and a top rim. The tubular structure has a frusto-conical shape and is vertically and co-axially disposed within the floater. The tubular structure having a widest diameter end disposed on the bottom rim and a narrower diameter end disposed at the top rim. This humidifier also has an air-supply arrangement that eliminates water damage to the fan during spillage.