It is quite common to see the use of phrases such as “best endeavours” or “reasonable endeavours” incorporated in one or more charter party clauses. These phrases are used in clauses relating to e.g. stevedore damage, in oil major approvals clauses and other types of clauses. It is therefore useful to have an idea about what best or reasonable endeavours mean: it is certainly not unusual to come across the view that reasonable endeavours means that (just) reasonable action etc. should be taken whereas best endeavours is quite commonly argued to be that virtually everything (perhaps even to the extent of being financially crippling) should be done with little restriction on the efforts to be made. It is not straightforward to give exact guidance on what is required by either reasonable or best endeavours clauses. Much will probably depend on the type of duty which is subject to this kind of “endeavours clause” and on the factual circumstances. In 2010, the English High Court made a judgment concerning a contract where one party was to use “all reasonable but commercially prudent endeavours to enable the achievement of the various threshold events.” Even though this case concerned a property redevelopment, the judgment is nevertheless a renewed reminder of what reasonable or best endeavours will require. If a charter party includes a requirement that “best endeavours” should be exercised, then it is important to recognise that this does, in fact, not mean that virtually everything (including a disregard of costs etc.) should be done: there are, after all, limits to even what “best endeavours” will require. This particular phrase has been dealt with by the English courts over a significant number of years. These cases are primarily not shipping cases but the principles expressed in case law will nevertheless be relevant for charter party disputes over what best endeavours will require a party to do. The words “best endeavours” have been said to require a party “to leav