An illuminating apparatus includes a lamp member, a lighting member, a waterproof member, and cooling liquid. The lamp member has a closed chamber, in which the cooling liquid is filled. The lamp member has at least a metal heat sink in the chamber, and the heat sink has at least a slot. The lighting member is isolated from the cooling liquid by the waterproof member. Therefore, the heat of the light emitting diode may be dissipated quickly through the cooling liquid.