One year, it was very hot the first week of April and we were on our way to Sevilla for Semana Santa. My wife's cousin (mid-40's) drove me to a Corté Inglés and bought me a pair of Spanish-made walking shorts. They came in very handy in Sevilla.
Also, on the subject of Speedo's: Speedo is a brand name and although they make thong-type swimwear, they also make swim trunks. I own two pairs of very fashionable Speedo swim trunks and I wear them whenever I go to the beach (in Spain or the U.S.). I last wore them bathing in the mar Cantabrico last September.