Penguins are the utmost specialized wing-propelled divers as their flapping action is accountable for the entire underwater propulsion. However. numerical evidence of how efficient their underwater propulsion is has not been studied to date. Literature sources suggest that propulsive efficiency peaks when the Strouhal number (St) ranges between 0. https://www.jmannino.com/quick-save-Canon-imageCLASS-MF227dw-Monochrome-Multifunction-Laser-Printer-great-choice/