Lagos is a city in the Algarve, in the south of Portugal. There is a great variety of things to see; The city center is sculped with traditional architecture and colors from the region. Beaches vary in shape and style from long sandy beaches to almost private ones hidden by cliffs. Ponta da Piedade is a beautiful spot with a nice lighthouse from where you can make boat tours to the natural caves. The harbour in the morning is full of activity, if you like to wake up early don't miss it. Also the fish market is an interesting spot.
One of the more popular events in Lagos are the Dolphin Tours, different companies offer tours to see dolphins. While you might be unlucky to not see a dolphin, it's still worth it if you've ever wanted a ride on a high powered boat. There are many maritime activities to do in Lagos, search, compare and buy the best maritime activities on Seabookings, where you can find a wide range of activities, from boat trips, dives, kayak tours, surf lessons, coasteering, kites surf, and many other sea activities.
The nearest Airport is Faro, about 75km from Lagos. To get to Lagos from Lisbon, you could take train or bus. To take the train, you could buy the intercity ticket, leave from Entrecampos station in Lisbon, get off in Tunes, a few stops before Faro and then change to the regional train to Lagos.