The asymptotic of eigen frequencies and corresponding waves on the free surface and interface of a two-layer ideal heavy fluid is constructed in two cases: the fluid is almost uniform and the upper layer has a low density. The asymptotic formulae are jusitified under the condition that the volume of the fluid is bounded. For the problem of surface waves, travelling in a submerged or surface-piercing infinite cylinder, the sufficient conditions for localized solutions of the limit problems to exist are indicated, and the hypothesis on the inevitable trapping of a wave by the body, which does not intersect both surfaces, is also formulated.