Boca Pos Spaño is located on the private property of San Nicolaas abou. There are several dive sites located on this property. The gate to the property is closed, so you need a key to get to these dive sites.
The key is available from Uniek Curacao. You have to mail them to make an appointment. Because of this it is a good idea to plan for a two tank dive here.
Boca Pos Spaño is the most Eastern dive site on this property. Pos Spaño means Spanish Well, so apparently there is a well here with fresh water. Maybe that is what you see on the Eastern side of this beach. There is a patch of water with green algae separated from the see by the beach. This looks like fresh water to me.
There is a wide rubble beach. From there you can enter the water. Look for a place where there is not too much coral near the shore. When the sea is a bit rough it can be difficult to enter and especially to leave the water because of the amount of (dead) coral close to the shore. So be careful.
The drop-off is close by. After a few minutes of swimming you can go under water. The slope is a bit more steeply than at most other dive sites, somewhere between 50 and 60 degrees. The coral density is quite high although there are broad patches of sand. There is a nice mix of coral and sponges. There are lots of Orange Elephant Ear sponges. You can see that the place is quite undisturbed because there are some old and large sponges. A nice place to dive.
How to get there
Coming from the Eastern part of the island you take the road to Westpunt. That is for a large part the only road from the Eastern part toward the Western part of the island. Follow this road untill you see a roadsign with Soto on it. There you go left in the direction of Soto. You stay on that road for a long time. You pass the village of Soto. Stay on the same road and after some time you will reach a road sign with Boca Hulu, Boca Santu Pretu and Mushroom Forest on it (see picture). From thee you have to take the dirt road at your left hand side. Soon you reach the gate (closed). If you didn't pick up a key for this gate at Uniek Curacao, you have to dive elsewhere. Otherwise open the gate (and close it after you entered the plantation) and go on over the dirt road. There are wooden road signs on the plantation that show you the way to one of the 4 dive location at this plantation. For this dive location follow the signs to Boca Pos Spaño. Park your car anywhere on the beach. You are probably the only one there.