I see it !

The Central Pier is the lesser known third pier in Dun Laoghaire Marina.  Sandwiched between its two big brothers - East and West - this third pier is very protected and yet still very isolated.   Many people aren't even aware it exists or know how to access it.

So, no better reason to place a cache.

You are looking for a box within a box.  Please be careful not to let things inadvertently go splash when opening the outer container.

Also - unless you have strong fingernails - you may want to bring a small flat tool (e.g. a butter knife) to help open the first lid, as it is quite firm and completely water-tight.

Good luck.