UNLOS is up to 200 nautical miles for economic zones - and that include extracting any oil and gas underneath it.
Its NOT up to Israel to set limits of 6 nautical miles here and 15 there.
Israel have no legal rights to the territorial waters of Gaza. That means any ship can come and go as they please - with the expressed permission of the Gazan authority - not dependent on Israeli authority. Unless Gaza is under Israeli Occupation - which it is.
Gazan have never ceded controls over its airspace and seas via any written agreement or via International Law.
Israel unilaterally imposed these restrictions. Gaza is locked down from the air and seas. Gazan can't sail their boat/ship or fly their plane to Egypt or Cyprus without Israeli permission.
