It looks like a kind of Sami sieidi. Though the Sami make them larger and more complex. I think that the Sami also use such pyramids in the depths of the island for a landmark, like their Canadian counterparts. It's probably pointless on the coast.

As far as I know, if the Sami sieidi is installed on the shore, then it is associated with a fisherman from the tribe. Going to sea, a fisherman leaves a part of his soul in the sieidi, so if he dies, his soul can return to his native lands.

But since these pyramids are mostly left by tourists, I think they have no meaning. It's probably like throwing a coin into a fountain.