The Mediterranean salt tongue is one of the most prominent features of
the North Atlantic at the thermocline level, resulting from the overflow
of saline Mediterranean Water through the Strait of Gibraltar. The
Mediterranean Water (MW) initially flows in a narrow boundary
undercurrent along the continental slopes of Spain and Portugal.
Starting near Cape St. Vincent, the MW spreads laterally into the
interior via submesoscale vortices (meddies) and other processes. Our
understanding of how MW spreads into the Atlantic has been mainly
inferred from hydrographic observations. Here we focus on direct
measurements of MW spreading with subsurface acoustically-tracked floats
that were sequentially launched in the undercurrent south of Portugal.
Based on these observations, we find that the Lagrangian integral time
scale is relatively short, 3-4 days, compared to the western North
Atlantic (10 days). Eddy kinetic energy levels are high in the
undercurrent south of Portugal, exceeding 100 cm^2/s^2, possibly due 
to the flow of the undercurrent past several large submarine canyons. 
Transforming the float velocities into bathymetric coordinates, it is 
clear that the undercurrent changes character abruptly around Cape 
St. Vincent, evolving from a strong jet-like current with peak mean 
speed of 15-20 cm/s, to a weaker current with peak speeds of only 
5-10 cm/s. As well as being sites of meddy formation, Cape St. Vincent 
and the Estremadura Promontory  are regions of enhanced eddy kinetic 
energy for the background flow field. The float tracks also show how 
the presence of meddies forming along the slope can divert the 
undercurrent offshore, representing an indirect effect of meddies on 
MW spreading.