[SNIP]
On the rocks at the small beach below the fortaleza there is an old big rectangular drain outlet there is a photo somewhere of two exsoldier searchers checking it but I don't know where it drains from. (Pegasus)
[At the small beach it is not a pipe, it looks much older, see the last outlet here http://www.mccannfiles.com/id340.html] (Pegasus)
This big opening?

This tunnel comes out on to the small rocky beach where there was much speculation that a boat may have been lying, or one may have come in for pick up. The channel you see was almost certianly natural, NOT cut, and it may well travel in for a really good distance. In which case I wonder which buildings might it have linked to?
1) The Fortaleza? which was an expensive looking restaurant when we were there? Old forts do sometimes have ancient tunnels radiating out
2) The Bull pub? If it was used for smuggling this could have been the link to it.
3) The house adjacent to the pub, or the house behind, on the seashore side of that house?
These natural phenomenas can be extremely long. In Puerto de la Cruz, Tenerife, [which is volcanic in origin, as I believe PdL is] there is a rift in the ground where one massive area of the ground is raised about 15 stories high, for over a quarter of a mile. This rift is running in a more or less straight line
If the tunnel that we see the entrance to, went back that far in a straight line, it would reach Ocean Club apartments passing Sergie Malinkas place en route.
I must make it clear that I am not a geologist.
I am only speculating, but I do wonder why the entrance has been filled with branches ... Is it something to do with Madeleines abduction? .... is it to stop people tracing the tunnel back to its source? .... to where she vanished out of sight?
...... and there are other things about this that I haven't the time, energy, or inclination to go into at present.
Several months ago, I worked with someone else on this and I need help from that person, before I can progress any further. It will be after Christmas if we decide to share.