Irish Sea dumps versus a Thames ammunition wreck

Which would have greater impact: the Irish Sea munitions dumps, including chemical weapons, or the ammunition wreck in the Thames?

The answer favours the Thames wreck as the greater explosive threat because of its position near flood defences; it does not assess chemical contamination.

The comparison is answered in terms of explosive effects. Deep water is expected to dissipate much of the energy from an Irish Sea detonation. The Thames wreck is considered more dangerous because of its location, with damage to flood defences raised as a possible consequence if enough explosive remains viable. That is the prediction offered in the discussion. The question also mentions chemical weapons in the Irish Sea dumps, but that hazard is not assessed.