From Facebook Lost Edinburgh

Portobello Bathing Pool, famous for its distinctive Art Deco design, lofty diving boards, artificial waves and chilly waters, was Portobello’s main attraction for over 40 years. The pool, which opened in 1936, was the largest outdoor facility of its kind in Europe. The Pool was enormous; 330 feet long by 150 feet wide – the equivalent of two Olympic sized pools – and varied in depth from one foot to six feet two inches at the deep end. Six thousand spectators could be accommodated, with 2,000 seats available under a cantilevered stand, and there were lockers provided for 1284 swimmers. The one and a half million gallons of water required to fill the pool was filtered from the sea and heated to a temperature of 68 degrees Fahrenheit by steam from the adjacent power station – though most accounts of the water temperature ranged from icy cold to sub-Siberian.
The pool’s great innovation was the first ever wave-making machine in Scotland. This consisted of four 24-feet long pistons mounted in a chamber at the deep end of the pool, which were arranged to send 3-feet high waves in three possible directions. These artificial waves were so dramatic that the machine was only operated after a warning on a klaxon had been sounded.
The Pool was closed for six years during the Second World War and had to be camouflaged to stop it being used as a landmark by enemy planes. It re-opened in June, 1946 and, unperturbed by the icy water conditions, the 1950s saw visitor numbers soar during the summer months with the queue to gain entrance often stretching the full length of Westbank Street. In the early part of the decade Sean Connery could be found at the Pool acting as a lifeguard.
By the end of the decade, Portobello’s popularity had waned as cheap package trips abroad became more readily available and people looked for more exotic locations for their holidays. The Pool fell into a long and controversial decline, with the closure of the power station in 1978 removing what little heat there was for the water. The 1979 season turned out to be the last and demolition was finally approved in 1988.

Contribution from Mr A Lightbody D.I.S.R.M

Mr A Lightbody D.I.S.R.M was employed at the Portobello Open Air Bathing Pool and provided the following information by letter  in January 1996
Portobello Open Air Bathing Pool was opened 30th May 1936.
Wave making machinery was designed, patented and supplied by Brown Brothers & Co Ltd Rosebank Ironworks Works Edinburgh.
Operation of Wave Making Equipment
The plant was situated at the deep-end of the pool. In a chamber behind a grille were four plungers each 24ft long. The plungers were moved up and down by means of connecting rods and arms situated in the machinery chamber behind and capable of developing waves from a ripple to 3ft high.
N.B Extract from the official programme souvenir of the pool opening.

Whilst the waves were very a popular feature of the pool operating for about 10 minutes every half hour. The size of the pool 330ft long 150ft wide and depth 1ft to 6ft 6 inches at the deep end.
The machinery required a considerable housing space. It was very noisy in operation and caused a lot of vibration in and around the plant room area which may have resulted in some structural damage.
Due to the dimension of the pool and heavy bating loads and in order to make the waves reach the shallow end of the pool the waves had to be very high at the deep end resulting in a back wash from the shelving beach making a millrace type of current returning down the middle of the pool. This created a dangerous situation where non-swimmers could and were washed out of their depths.
Safety ropes had to be provided across the pool mid-way and during wave periods pool attendants were kept busy rescuing the bathers swept off their feet.