Natación vs. nado
In Spanish, both 'natación' and 'nado' refer to swimming, but they have different usages and connotations.
Natación
'Natación' specifically refers to the sport or activity of swimming. It is often used in formal contexts and when talking about swimming as an organized sport or training.
Ella practica natación todos los días en el club.
(She practices swimming every day at the club.)
El equipo de natación ganó la competencia estatal.
(The swimming team won the state competition.)
Las clases de natación comienzan a las siete de la mañana.
(The swimming classes start at seven in the morning.)
Nado
'Nado' refers more generally to the action of swimming. It is used in less formal contexts and can describe the act of swimming itself, rather than the sport.
Disfruté mucho mi nado en el lago esta mañana.
(I really enjoyed my swim in the lake this morning.)
Su estilo de nado es muy elegante.
(Her swimming style is very elegant.)
Después de un largo nado, se sintió revitalizado.
(After a long swim, he felt revitalized.)
Summary
In summary, 'natación' is used predominantly to refer to the sport or organized activity of swimming, whereas 'nado' typically describes the act of swimming itself.