The sea level difference either side of the Panama Canal is approx. 20 cm (higher on the Pacific side) - see for example, Pugh, D.T. 1987, "Tides, surges and mean sea-level", Wiley. RLR 1964 datum at Balboa is 3.112 m below the "Tide Staff Zero" which is itself 12 feet below Panama Canal Precise Level Datum (PLD). On the Atlantic side, at Coco Solo RLR 1993 is 6.288m below the Tide Staff Zero which is itself 2 feet below PLD there. For the older Cristobal data, RLR 1964 is 6.138 m below the Tide Staff Zero which is itself 2 feet below PLD. From inspection of RLR data and from this information, one can indeed verify that sea level is higher on the Pacific side by about 20 cm. However, the accuracy of the PLD national levelling system is unclear.
Documentation added 2012-01-26
This is an historic station although still mentioned on the NOAA website there is now very little information regarding the former tide gauge site. Last data received is that for December 1968. Station has been marked 'inactive'.