PC excursions advice

[arlopop]

We are doing the EBPC this year. My MIL just booked a cabin to join us. She is not in the best of shape but still has an interest in doing an excursion (sight seeing). She expressed an interest in Cartagena. I just can't figure out what would be a non-strenuous choice for her or what to expect in terms of temperature in the beginning of September.

I'm hoping somebody can help me out with this.