Suppose one were given the task of mapping the general circulation in an unfamiliar ocean. The ocean, like our own, is subdivided into basins and marginal seas interconnected by sea straits. Assuming a limited budget for this undertaking, one would do well to choose the straits as observational starting points. To begin with, the currents flowing from one basin to the next, over possibly wide and time-varying paths, are confined to narrow and stable routes within the straits. Mass, heat and chemical budgets for individual basins can be formulated in terms of the fluxes measured across the straits using a relatively small number of instruments. The confinement of the flow by a strait can also give rise to profound dynamical conse­ quences including choking or hydraulic control, a process similar to that by which a dam regulates the flow from a reservoir. The funneling geometry can lead to enhanced tidal modulation and increased velocities, giving rise to local instabilities, mixing, internal bores, jumps, and other striking hydraulic and fine scale phenomena. In short, sea straits repre­ sent choke points which are observationally and dynamically strategic and which contain a full range of fascinating physical processes.

I. Case Studies.- Characteristics of Circulation in an Indonesian Archipelago Strait from Hydrography, Current Measurements and Modeling Results*Indicates peer-review paper.- On the Physical Oceanography of the Turkish Straits*.- A Review of the Physical Oceanography of Fram Strait*.- Tidal Currents and Transient Phenomena in the Strait of Messina: A Review*.- Measurements and Modelling in the Great Belt: A Unique Opportunity for Model Verification*.- Zero Blocking Solution for the Great Belt Link.- The Flow Through Vitiaz Strait and St. George's Channel, Papua New Guinea.- A Review of Recent Physical Investigations on the Straits Around the Japanese Islands.- Influence of the Climatic Conditions on the Winter Fluxes in the Corsican Channel.- Long Term Current and Sea Level Measurements Conducted at Bosphorus.- WOCE and the Gibraltar Experiment Third Objective.- II. Hydraulics.- Hydraulic Models of Deep Stratified Flows over Topography*.- Is the Exchange Through the Strait of Gibraltar Maximal or Submaximal?*.- Aspiration of Deep Waters Through Straits*.- A Review of Rotating Hydraulics*.- Rotating Two-Layer Sill Flows*.- Role of Laboratory Experiments and Models in the Study of Sea Strait Processes*.- III. Waves, Tides and Time-Dependence.- Review of Dispersive and Resonant Effects in Internal Wave Propagation*.- Time-Dependent, Two-Layer Flow Over a Sill.- Long Progressive Waves in Rotating Fluid.- Characteristic Features Occurring in the Strait of Gibraltar as Seen Through Remote Sensing Data.- The Barotropic Tide in the Strait of Gibraltar.- Generation and Kinematics of the Internal Tide in the Strait of Gibraltar.- The Structure of the Internal Bore in the Strait of Gibraltar and Its Influence on the Atlantic Inflow.- Transients in the Nonlinear Adjustment toGeostrophy.- IV. Outflows, Turbulence and Mixing.- Can Mixing in Exchange Flows be Predicted Using Internal Hydraulics?*.- A Simple Model of the Descending Mediterranean Outflow Plume.- Friction in a Shallow Two-Layer Flow in a Rotating Ocean.- The Breakup of Outflows and the Formation of 'Meddies'.- The Dynamics of Two Dimensional Turbulence.- V. Current Research Problems.- Current Research Problems.