Portugal’s largest cave system, 14km southeast of Porto de Mós is very touristy and old-fashioned, although the caves themselves are impressive. The 45-minute tour's spiralling 110m descent leads through psychedelically-lit chambers to a final cavern containing a lake with a rather hokey fountain display. There's also a children's zoo here and an aquapark. There are three buses weekdays from Porto de Mós (€2.45, 35 minutes). From July to mid-September there’s also weekend service.
