Abstract: The article contains analysis of various issues regarding interpretation of the UN Convention on the Law of the Sea of 1982, which were faced by the International Tribunal for the Law of the Sea (ITLOS) in the course of dealing with the cases on immediate release of seized vessels and their crews. The main part of the problem is dealt with based upon the judicial practice of the International Tribunal for the Law of the sea. The author uncovers the main tendencies in the judicial practice of the International Tribunal for the Law of the Sea, novelties and norm-making of this judicial body on the issues of immediate release of the seized vessels and their crews. The author studies the issues of confiscation (of a fishing boat in cases on unlawful fishing in an exclusive economic zone), bails and material guarantees, grounds for the seizure of foreign vessels in an exclusive economic zone, procedural issues regarding admissibility of claims for the International Tribunal for the Law of the Sea (namely, presence of a real connection between a vessel and a protecting state, the need to exhaust the local legal remedies, presence of sufficient evidence).