Would it be possible to build a massive seawall, say maybe even made from metal that could rise as the sea level rises to prevent being erased?

I am not considering costs here, nor beauty, only if such a wall would be able to resist the force of the entire ocean trying to get into the "empty" pool.

  1. Is it feasible?
  2. What kind of material would be required? How high could one go?
  3. In the event of a leak, "terrorist" assault, what kind of disasters and how quickly would the Island become "erased"

You can give an example approximation on the size of the Island.

Just theoretical.


1 Answer 1


This is more of an engineering question. For some situations it may be possible to build such a wall around some islands. Such a sea wall would be a cofferdam, which have been used for small scale temporary projects.

Complicating factors would be:

  • The height of the sea wall and how much water would need to be held back.
  • The depth of to the sea floor. If the island is the tip of a seamount with steep sides and a large depth to the sea floor then a sea wall would be impossible.
  • The depth into the sea bed that the wall would need to be anchored into, or the wall would need to sink into, for the wall to be stable.
  • The wall would have to be able to withstand typhoons/cyclones/hurricanes, small tsunamis and seismic events.

A metal wall would not be a long term solution due to corrosion of the metal. The most suitable material would be rock or concrete. Such a wall would need to be very wide. However, over time, even such a wall would need to be replaced/repaired due to sea erosion and battering.

Securing the wall against leaks would be critical and such a system may require solar power pumps to continuously move excess water out of the enclosure.

  • $\begingroup$ Thanks, i will look into cofferdams more. But it appears to be somewhat possible. Seamont would make it impossible? Is it not just to build the wall so it is at the same height .. and if some areas are higher in some place, you can just ingore building the wall ... $\endgroup$
    – mjs
    Dec 22, 2017 at 10:49
  • $\begingroup$ The size of the region to be enclosed, the steepness of the submerged terrain & the depth to a stable base make some seamounts very difficult propositions. Acquiring sufficient material to make a wall would be very difficult. $\endgroup$
    – Fred
    Dec 22, 2017 at 11:32
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    $\begingroup$ Just one example, but a very appropriate one is en.wikipedia.org/wiki/Flood_control_in_the_Netherlands $\endgroup$
    – arkaia
    Dec 22, 2017 at 16:16
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    $\begingroup$ I'd also note that, as with many engineering-based solutions to environmental changes, building structures to separate the land surface from the ocean would affect the local environment. (For example, sea turtles climb onto land to lay their eggs in the sand.) Addressing undesired impacts would affect the feasibility of the project. $\endgroup$ Dec 22, 2017 at 21:40

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