Cartagena is a busy summer resort that has a long stretch of nondescript beachbreak that leads north to a cove called Las Cruces. When the sand builds up a good left can start at the southern headland and zip across the bay. Often just a mushy closeout, at least it has a bit of speed and is worth a look.
It's crowded in summer with beach goers and bodyboarders. Pay to park as well.