Just an hour's boat trip away from Cartagena lie the magnificent Rosario Islands, which belong to Colombia's only underwater natural park (Rosario and San Bernardo Corals National Natural Park). Abundant marine wildlife (including over 50 species of corals) and some of Colombia's best beaches draw in many in search of relaxation and active pursuits such as snorkelling and diving. Isla Grande is best for kayaking through unique mangrove forests and seeing the phosphorescent plankton light up the waters of a brackish lake at night, while Playa Blanca is Cartagena's most spectacular white-sand beach (also reachable by land). It should be said that the company you choose to tour with has the potential to make or break the experience. Low cost tours can mean multiple intermediate stops en route to your destination, as well as unpleasant surprises such as no transfer back to your hotel. Try and choose a trusted company with consistently good reviews, or opt for a private tour. Mind that seas may be rough at certain times of the year, particularly in December and January, when tours on smaller boats may even become dangerous.

Famous Greek monuments and splendid artworks from different historical periods are exhibited at The Archaeological Museum of Kos. The most extraordinary displays here include beautiful mosaics, statues from the ancient site of Asklepeion, an extensive collection of prehistoric pottery and metallic objects, exhibits from a tomb of a young athlete dating back to the 3rd century B.C, coins, anaglyphs with various representations and many other items.

The Dolphin Fountain is a popular tourist spot on Kos, situated on a small square along the harbour.

The mangrove tunnels of nearby La Boquilla are an easy day trip from Cartagena. Guided tours will often combine a visit to the beach (one of the Playas De La Boquilla) with a boat or canoe tour of the mangroves, passing through Cienaga de Juan Polo and the Cienaga de la Virgen lagoons. Some tours will also include a closer encounter with local fishermen and offer insight into their craft. La Boquilla is an area of contrasts: the district of upscale hotels — Morros — borders on humble neighbourhoods populated by workers. When sitting down to tuck into no-frills seafood dishes served up by local eateries, make sure you're clear about the price of each item ordered from the get-go, as there have been reports of "surprise" bills amounting to several hundred US dollars.