Santa Marta is one of Colombia's most popular Caribbean beach resorts. This is a video of one of Santa Marta's beaches - which are rather crowded, especially during the peak tourism season. For a more laid back location, Taganga is a smaller resort just 10 minutes away, or Park Tayrona is even more empty and idyllic, and about 1 hours travel away.
Santa Marta - one of Colombia's premier beach resorts. Eat carefully, and don't touch the tap water - I got extreme food poisoning here.
Here's a video of some of the beaches around Taganga, shown at the beginning of the clip. The latter clips are of the amazing Park Tayrona.
Colombia's coastline is quite beautiful, and many regions remain wonderfully underdeveloped. See the section on beaches of Colombia for further beach resort ideas.
Santa Marta during peak tourism season can get very crowded.
Santa Marta has fine beaches in town and nearby, but Taganga is more laid back:
Taganga, a nearby small fishing village, is far more laid back and relaxing.