I had been looking at Nagi no Asukara for a while and I didn't really want to watch it because it looked like a mediocre, boring anime and I had that mentality at first watching it. However over time I started to love it more and more. If you don't think you want to watch this because of its cover please do change your mind.
I think to me Nagi no Asukara has the most beautiful art in the anime world from my perspective. I'm from Hawaii so seeing fish and the sea around the charecters made it feel like a dream. I love fish and the ocean is a place where I have made many fun memories so seeing the charecters breathing and living underwater felt cool