Hi!
Well, "akin to you", means :like you,identical to you..
Well..it's a poem..
The meaning is that in Paradise, he found a place that looks like his love and he marked that place.
He also found a house by the sea.
It's only two lines for a whole poem!
"In Paradise I have marked an island...
akin to you, and a house by the sea
with a big bed and a small door
I've cast an echo into the bottomless deeps
To see myself every morning when I wake up
to look at you getting half in the water
and half to mourn you in Paradise.."
I sent you a little bit more!