area
barbed
barrier
border
close
concertina
construction
danger
defense
design
entanglement
factory
fence
ferry
harbor
industrial
insurance
iron
maritime
mesh
mess
metal
muddle
object
obstacle
obstruction
outdoors
passenger
prison
prohibition
protection
razor
restriction
scroll
sea
seaport
sector
security
separating
ship
site
spiral
steel
sunrise
surround
transport
travel
wire
zone