hI, we did this as a day trip recently and really enjoyed it.
Don't get up too early, but then take a leisurely drive to Cartagena and once there follow the signs for the Puerto. Park underground (near Burger King on the harbour side ) and then havea leisurely stroll up and down the quay and stop for coffee. Cross the road and wander over to the old town and pay 5 euros for a visit to the Roman ampitheatre and museum - well worth it. Come out and wander round the old town and pick any of the great Spanish restaurants for tapas. After a quantity of cerveza or red wine wander back to the Port and do "one last trip round the bay" on the tourist boat (again about 6 - 8 euros). Finish off the day with dinner back at El Patio.
It was a good day out, leisurely with something for everyone. Oh and I forgot - there are one or 2 very nice shops in the Old Town too!
Enjoy
Sandra
f