This thesis discusses the nature of sea carriers' implied obligations of seaworthiness, care of cargo and non-deviation from the voyage route, at common law and under the Hague and Hague-Visby Rules, and their effect on clauses which seek to exclude or modify them. After a consideration of the historical evolution and nature of the implied obligations, the standards of performance imposed under them at common law is considered before going on to how the peculiar nature of the obligations lead to modified results under the general contract law rules for the construction of exclusion clauses. The discussion proceeds to the standards of the obligations imposed on the carrier by the Hague and Hague-Visby Rules to exercise due diligence to make the vessel seaworthy and to properly and carefully carry the cargo. There is a consideration of the significance of the overriding, as well as the non-delegable nature of these obligations. In particular, whether or not a carrier whose breach of an implied obligation is a cause of the loss or damage to cargo, can rely on the exceptions provided by the Rules is considered in depth. The final sections of the thesis deal with the principles of causation and onus of proof applied in sea cargo claims and how they impact upon the interface between the implied obligations and exclusion clauses. The analysis of causation examines how liability is determined where the carrier's breach of an implied obligation co-operates with or is intervened upon by an excepted peril to produce the loss or damage to cargo. With respect to onus of proof, the issue considered is which party bears the legal burden on proof or disproof of the breach of an implied obligation: must the cargo owner establish affirmatively that the particular breach asserted caused his loss or is it for the carrier, as part of his defence, and claim for exemption from liability. to negative breach? The thesis advances two principal arguments. First, it is argued that because of the development of the implied obligations of seaworthiness, care of cargo and non-deviation from route as important obligations which underlie the carriage contract, strict and utmost care standards of performance are imposed under them at common law and under the Hague-Visby Rules respectively. Secondly, it is argued that the result of these high standards of performance is that there is a "risk" approach to liability which explains the peculiar rules of construction, causation and onus of proof which import restriction on the effect of sea carriers' exclusion clauses.