What time of year did you go? Is it possible to drive to Carti in your own vehicle and just get on a ferry to one of the islands?
We went in February of 2017 and the ferry to Columbia wrecked on a sandbar and was not running at that time. I am not sure if it stops at different island along the way.
Only with a 4x4 vehicle. You need to leave very early in the morning to reach the boats. You can also look for a day tour only for boat and visit 3 islands in one day, which is the regular. Visit panama san blas tours (point) com
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