<html><head></head><body><div style="color:#000; background-color:#fff; font-family:Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:13px"><div id="yui_3_16_0_ym19_1_1498917491013_2542">Hi all,</div><div id="yui_3_16_0_ym19_1_1498917491013_2542" dir="ltr">How do deep diving subs deal with external O2 supply. Does Alvin have external tanks for O2, are they super special tanks?</div><div id="yui_3_16_0_ym19_1_1498917491013_2542" dir="ltr">Hank</div></div></body></html>