Please note that the High Seas is the area outside the Exclusive Economic Zone (200 nm)
However, Article 73 explicitly states that
jurisdiction within the Exclusive Economic Zone is limited to ensuring compliance with laws regarding the economic exploitation of the Zone. Boardings and any other actions enacting jurisdiction are only permitted within that legal limit.
Also, any warship has the right in intercept, inspect, and seize a vessel on the high seas that is not flying the flag of its country of registry
Sure, but we've already moved past that in the discussion. On a side note, submarines and submersibles do not need to fly flags.