Koufonissi has the bluest and most brilliantly transparent and clear waters in all of the Cycladic islands. Deep blues out at sea, turquoise blues near the sandy beaches, a sea that is pure and crystal clear.
Proof of the saying is that in Pano Koufonissi, the largest beach is the one by the port itself, two steps from the village itself and is a favourite for those who don't feel like walking to the other beaches.
The rest of the beaches, all on the eastern side of the island are in turn:
At Harokopoum Foinikas beach, the one which is a favourite with families and is a 10 minute walk from the port or Gitonia tis Irinis.
The next one is Fanos beach, a favourite with the younger generation who like sea sports and surfing, and several smaller coves for those who wish for some privacy; at Geranaki and Plateia Pounta or Italida, as it is better known. This is the beach with the loveliest waters in all of the Cyclades and certainly the most popular one on the island.
After Italida beach, you can find many small coves with sand or pebbles as well as many rocky caves, ideal for those who like to swim on their own. The most interesting one of those is the called the Swimming Pool (Pissina), which is a large hole in the rocks that really does look like a swimming pool, and most people stop there even for a quick dive.
The great beach of Pori, one of the most beautiful beaches on the island, is about a half hour's walk from the village, along a beautiful walk by the sea. The beach can be reached by another road through the island's interior which is about the same distance.
A little beyond Pori, is the renown Gala (which means 'milk' in Greek), an open cave which connects to the sea through a narrow opening and has taken its name by the white frothy waves which hit it when they go into the interior of the cave. It is a beautiful location with a small pebbled beach - and you can really hear the whisper caused by the sound of the pebbles when they are carried by the water.
Behind Pori, at the Xylovates coast which looks across towards Naxos, is the pleasure of the daring visitor who loves to dive from the high rocks. The waters are so beautiful that most people are indeed tempted to try the dive, but few actually dare to do so!
At Kato (Lower) Koufonisi island, the beautiful beaches at Deti, at Nero, at Pezoulia and northern most at Fikio, all isolated and peaceful and one can walk to them quite easily. The most distant one, Pezoulia, is about one hour's walk from the small port of Kato Koufonissi.
Keros island, across the bay, does not actually have sandy beaches, but you can swim in crystal clear and transparent waters - something you can do on all the smaller islands around Koufonisi.