Plane submerged water jets which issue from nozzle into quiescent water in channel have been known to attach to the adjacent solid or free surface owing to the Coanda effect. This paper is concerned with an experimental investigation on the plane submerged jets. Flows are visualized by using hydrogen bubbles and tracer particles. The photographs show that the jets attaching to the free surface are classified into six types according to their behavior after issuing from the nozzle. Under some limited conditions, the free surface is found to make self-induced vibration. The velocity distributions are given in the form of the vector diagram and the flow patterns made in the channel for each type of the jets are indicated. The flow visualization by tracer particle method provides that the jets attaching to the free surface diffuse faster than those attaching to the solid boundary.