Thalassotherapy is perhaps less an alternative medicine than a treatment for specific ailments. It has witnessed ups and downs. A centuries-old, if not millennia-old, approach, it has gained many adepts in the medical profession and left many a patient delighted with its results. Thalassotherapy has many aspects in common with thermalism that, similarly, gained its lettres de noblesse over the centuries. This paper examines the roles that thalassotherapy has played and currently plays and surveys the European centers that have gained a solid reputation for thalassotherapy. It concomitantly considers its parallel therapy—thermalism—and takes a look at other related alternative or complementary treatments. The economic impact of thalassotherapy and its related activities has increased.