Warning signs about tombstoning have been placed at piers and harbours.
Port authorities are highlighting the dangers of jumping into or swimming in harbours.
A spokesman said: 'Officers are concerned that members of the public, particularly children and young people, are not aware of the dangers from boats manoeuvring, the shock that can occur from entering cold water suddenly and the hazard presented by not knowing the depth of the water.
'Although we have been fortunate in the Isle of Man not to have had any serious accidents this is not the case in the UK where there have been several well- publicised incidents of people suffering severe injury as a result of tombstoning.'
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