Clue number 4

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Across
  1. 3. Beneath or below
  2. 4. Synthetic material that can be moulded into various shapes
  3. 6. What do tunnels go through?
  4. 7. Protective outer layer
  5. 8. container made of flexible material used for carrying items (your friends do too many of them on the weekend)
Down
  1. 1. Open or available to everyone
  2. 2. Structure that extends from the shore into the water
  3. 5. Small, sheltered bay
  4. 6. A way for vehicles and pedestrians to travel