I was going to say the same. There is a chance that they sailed to the location. However a 6 hour flight from the closest major city would have given off 1500

I was going to say the same. There is a chance that they sailed to the location. However a 6 hour flight from the closest major city would have given off 1500 kg of CO2 (per passenger). And presumably another 1500kg to get back again.