We actually enjoyed our stay in San Blas, but nothing was as listed when we booked. Rather than going to Aguja, we were dropped at an island called Icodub. There was no snorkeling on the way to the island either. Actually, the next day, I was told that they were waiting for us to go snorkeling, but no one explained the change.
When you arrive at the boat launch, along with dozens of others, it is like a cattle call. You are simply told to wait in a certain spot, which boat to get on when, and when to get off. Perhaps if you are fluent in Spanish you can sort these things out, but even though we know enough to ask basic questions, we were simply told this is what we have to do.