On 5 August 1936 the so-called Convoy de la victoria was able to bring at least 2,500 men across the Strait, breaking the republican blockade. Communications The Strait is an important shipping route from the Mediterranean to the Atlantic. There are ferries that operate between Spain and Morocco across the Strait, as well as between Spain and Ceuta and Gibraltar to Tangier. Tunnel across the Strait Discussion between Spain and Morocco of a tunnel under the strait began in the 1980s. In December 2003, both countries agreed to explore the construction of an undersea rail tunnel to connect their rail systems across the Strait. The gauge of the rail would be to match the proposed construction and conversion of significant parts of the existing broad gauge system to standard gauge. While the project remained in a planning phase, Spanish and Moroccan officials met to discuss it occasionally, including in 2012. Those talks led to nothing constructive happening, but in April 2021 ministers from both countries agreed to a joint intergovernmental meeting to be held in Casablanca in the coming months. This was in order to resume discussions on a tunnel. Earlier, in January 2021, the UK government had studied plans for a tunnel to link Gibraltar with Tangiers that would replace the Spanish-Moroccan project that until then had had no tangible results after over 40 years of discussions. Special flow and wave patterns The Strait of Gibraltar links the Atlantic Ocean directly to the Mediterranean Sea. This direct linkage creates certain unique flow and wave patterns. These unique patterns are created due to the interaction of various regional and global evaporative forces, water temperatures, tidal forces, and wind forces. Inflow and outflow Water flows through the Strait more or less continuously eastwards and westwards. A smaller amount of deeper saltier and therefore denser waters continually work their way westwards the Mediterranean outflow, while a larger amount of surface waters with lower salinity and density continually work their way eastwards the Mediterranean inflow. These general flow tendencies may be occasionally interrupted for brief periods by temporary tidal flows, depending on various lunar and solar alignments. Still, on the whole and over time, the balance of the water flow is eastwards, due to an evaporation rate within the Mediterranean basin higher than the combined inflow of all the rivers that empty into it. At the Strait's far western end is the Camarinal