A semi-submersible floating platform for use in offshore applications having a semi-submersible hull structure including motion damping support columns, a pontoon structure adjoined to the motion damping support columns at a lower end thereof, and a deck structure supported at an upper end of thereof for supporting equipment mounted thereon above the water surface. Each motion damping support column has an inner water trapping damper chamber of closed base or open base construction that allows natural flooding of said inner water trapping damper chamber during installation and before reaching an operating draft of the platform, and which when flooded provides hydrodynamic mass, damping, and in-water weight to said platform during operation. A plurality of smaller columns are disposed on the perimeter of the upper portion of each support column and surround the upper portion of the inner water trapping damper chamber.