Is it illegal to drop boulders into the sea?
<p>The BBC has a <a href="https://www.bbc.com/news/av/science-environment-56201231" rel="noreferrer">video</a> in which those opposing Greenpeace say so</p>
<blockquote>
<p>A Greenpeace ship has been dropping huge boulders into the sea off Brighton this week to stop fishing boats from trawling the sea bed. [...]</p>
<p>But leaders of the fishing community describe the action as dangerous, illegal and irresponsible.</p>
</blockquote>
<p>What UK law prohibits this and what is the penalty for breaking it?</p>

<p>The sea area in question is a <a href="https://en.m.wikipedia.org/wiki/Marine_protected_area" rel="nofollow noreferrer">Marine Protected Area</a>, which is referred to in the <a href="/questions/tagged/united-kingdom" class="post-tag" title="show questions tagged &#39;united-kingdom&#39;" rel="tag">united-kingdom</a> as a <a href="https://en.m.wikipedia.org/wiki/Marine_Conservation_Zone" rel="nofollow noreferrer">Marine Conservation Zone</a> (as per No17 on the 2016 linked list) and lies within the  <a href="https://www.legislation.gov.uk/ukpga/1987/49?timeline=false" rel="nofollow noreferrer">UK's territorial waters</a>.</p>
<p><strong>What UK law prohibits this?</strong></p>
<p>I have discounted my initial thoughts about <a href="https://www.legislation.gov.uk/ukpga/1995/21/section/58?timeline=false" rel="nofollow noreferrer">s.58(2) of the Merchant Shipping Act 1995</a> as I strongly suspect the Greenpeace vessel is neither UK registered nor proceeding to/from a UK port.</p>
<p>I have also considered the <a href="https://www.legislation.gov.uk/ukpga/1971/48/contents" rel="nofollow noreferrer">Criminal Damage Act 1971</a> which, although potentially viable* and has <a href="https://www.legislation.gov.uk/ukpga/Vict/41-42/73?timeline=false" rel="nofollow noreferrer">off-shore jurisdiction</a>, I have discounted in favour of the <a href="https://www.legislation.gov.uk/ukpga/2009/23/contents" rel="nofollow noreferrer"> Marine and Coastal Access Act 2009</a> which creates the offence of depositing objects in the UK's territorial waters without a licence:</p>
<p><a href="https://www.legislation.gov.uk/ukpga/2009/23/section/65?timeline=false" rel="nofollow noreferrer">s.65</a> <strong>Requirement for a Licence</strong></p>
<blockquote>
<p>(1) No person may -</p>
<p>(a) carry on a licensable marine activity
...
except in accordance with a marine licence granted by the appropriate licensing authority.</p>
</blockquote>
<p><a href="https://www.legislation.gov.uk/ukpga/2009/23/section/66?timeline=false" rel="nofollow noreferrer">s.66(1)</a> <strong>Licensable Marine Activity</strong> includes:</p>
<blockquote>
<p>1.(a) To deposit any substance or object within the UK marine licensing area, either in the sea or on or under the sea bed, from ... any ... vessel ...</p>
</blockquote>
<p><a href="https://www.legislation.gov.uk/ukpga/2009/23/section/66?timeline=false" rel="nofollow noreferrer">s.66(4)</a> states the &quot;UK marine licensing area” consists of the <em>UK Marine Area</em> which is defined by <a href="https://www.legislation.gov.uk/ukpga/2009/23/section/42?timeline=false" rel="nofollow noreferrer">s.42</a> to include:</p>
<blockquote>
<p>the area of sea within the seaward limits of the <a href="https://www.legislation.gov.uk/uksi/2014/1353/made" rel="nofollow noreferrer">territorial sea adjacent to the United Kingdom</a></p>
</blockquote>
<p><strong>What is the penalty?</strong></p>
<p><a href="https://www.legislation.gov.uk/ukpga/2009/23/section/85?timeline=false" rel="nofollow noreferrer">s.85(4)</a> states anyone guilty of a s.65(1) offence is liable:</p>
<blockquote>
<p>(a) on summary conviction, to a fine not exceeding £50,000,</p>
<p>(b) on conviction on indictment, to a fine or to imprisonment for a term not exceeding two years or to both.</p>
</blockquote>
<p>*relating to the seabed as well as the bottom trawlers.</p>

united-kingdom law-of-the-sea