The greenland map is almost impossible to get platinum on. The added boat coverage is glitched, which means that actually guessing the position by calculation gives wrong results because the coverage is apparently inside the terrain. Can be seen on boat coverage with the boat models Suzuki 140 and 240 (look for the number on the motor on the back) and also due to the sheer amount of boat coverage pictures in Google Street View, the likelihood of getting one is way too high. This makes consistent and calculated runs impossible.
EDIT: Just to clear things up: I'm not saying boat coverage should be removed. It's an interesting challenge - if it works and that's the point.
Here is an example of boat coverage in Greenland, the position of which can be calculated close enough for 5K
This however is not possible for most of the cases due to Google Maps being glitched. This is also problematic on Faroe Islands but not nearly as much for me to make a bug report for Faroe. The probability of glitchy boat coverage or glitched locations spawning (Qaannap for example) on the Greenland map is way too high so that this level simply becomes unfair instead of just a very hard challenge.