Due to the growth of their population, urban development and the corresponding expansion of land use, several countries have decided to build artificial islands in the sea to decrease the pressure on the heavily used land space. The reclamation of the land from the sea is already widely applied, however, there is also an attractive new alternative: construction of very large floating structures (VLFSs). VLFSs can and are already being used for storage facilities, industrial space, wind and solar power plants, bridges, ferry piers, docks, rescue bases, breakwaters, airports, entertainment facilities, military purposes, even habitation, and other purposes. They can be speedily constructed, exploited, and easily relocated, expanded, or removed. The subject of the dissertation is hydroelastic analysis of a very large floating structure, so the motion of a VLFS (modelled by an elastic plate) and its response to surface water waves. Several problems of the interaction between the VLFS and water waves are treated in the dissertation. The plate deflection, free-surface elevation, reflection and transmission of water waves are studied using different theories of applied mathematics, mechanics and hydrodynamics. New method for the hydroelastic analysis of the VLFSs, an integro-differential equation method, is proposed, justified, and applied in the dissertation. Also, the geometrical-optics approach, the ray method, and the Lindstedt method are used.\par An analytical solution and numerical results are derived for various shapes and dimensions of the floating plate and three different models of water depth. The problem background and introduction, literature survey and information on VLFSs are given in chapter 1. Chapter 2 describes the general theory, the basic equations and conditions, introduces and formulates particular problems considered, and proposes a method of solution. The problems for the following models and horizontal shapes of a very large floating platform are solved in chapters 3--7: a semi-infinite plate and a strip of infinite length, a circular plate, a ring-shaped plate, a quarter-infinite plate, and a plate of finite, but small, thickness. Analytical solutions together with representations and operations are described for specific cases. Numerical results are obtained for practically important and relevant situations.\par General conclusions, recommendations and a discussion on VLFSs in and of the future are given in chapter 8.