Complex sentence: Ultra-light aeroplanes are often equipped with floats, amphibious floats or designed as a seaplane, however, there is no seaplane rating for the ultra-light pilot permit.
Split into simpler sentences: Ultra-light aeroplanes are commonly equipped with floats, amphibious floats or designed as a seaplane. However, there is no "de jure" seaplane rating applicable to the ultra-light pilot permit.