A casing floatation system includes a casing having a pre-load collar and a landing collar; and a lower bottom latch-in plug comprising: a catch mechanism compatible with the pre-load collar; and a landing mechanism compatible with the landing collar. A method of well completion includes floating a casing in a wellbore with a casing floatation system having a pre-load collar; sequentially engaging a lower bottom latch-in plug and a top latch-in plug having a transitionable seal; pressure testing the casing; and triggering the transitionable seal to unseal the bore of the top latch-in plug.