It is unclear whether Law of the Sea tribunals under the Law of the Sea Convention (LOSC, or the Convention) have jurisdiction to determine maritime boundary disputes involving concurrent land sovereignty issues. The text of the Convention and case law are silent in this respect. The only reference is in LOSC Article 298(1)(a)(i), which allows States to make declarations exempting maritime delimitations from compulsory dispute settlement, excluding concurrent territorial questions even from conciliation. However, it leaves unclear whether concurrent land sovereignty issues are also excluded in the absence of such declarations. There are indications that LOS tribunals may be able to decide ancillary land issues so long as these do not constitute the ‘very subject-matter’ of the dispute, or rely on an alternative jurisdictional basis. The question of competence over mixed disputes may be less extensive in effect than is often believed. States should not avoid initiating proceedings based on the view that LOS tribunals might not ultimately exercise jurisdiction.