It has many holes for fish to swim through.
This is very light and won't weigh down your tank at all.
It is safe and suitable for both fresh and salt water tanks.
The measurements for each ship are approximately:
Front part of the ship: Length 27cm, Width 14cm, Height 21cm
Back part of the ship: Length 22cm, Width 14cm, Height 25cm
Total length at it's smallest is 45cm