An affordable and direct train service makes it easy to do a Cascais day trip from Lisbon, in under an hour. Cais do Sodré to Cascais, you cant mess it up. When you arrive just wander through town and you’ll eventually hit the marina. Take a stop at the tourism center for a free map. Then walk up the palm tree-lined street and around the edge of the water on a lovely wide promenade sidewalk. You can actually walk all the way to the Boca do Inferno in under 30 mins and its really nice (don’t forget sunscreen though!). On the way back I recommend getting a museum pass and stopping into any museum that looks interesting. Lots of gorgeous tile and mini-mansions to explore. If you’re interested in luxury cars I suggest lingering around the marina a bit…