Huhu,
soo after a little test and building an own realistic sea i get now this error message everytime its start ^^ also the waterlevel doesnt rise - so that the upper sea doesnt have enough water now xD
also you can see that i have reached the distancelimit ^^ they doesnt recognizes that there are task upside - only when i get them in party and send them their - then the dig orrrr they have probs because they should set items their and cant reach them xD
also you see on some pics that the goblins has spawned and was killed inside my boarder 
on the left side next to my walls 