I'm not sure what the format is of the exported Ocenlog data, but I have attached a sample of a dive in subsurface's XML format. I expect that with a little sed, awk, perl, or python -fu you should be able to translate the Oceanlog data into this xml format. From that, subsurface should be able to open the file natively.
This data was from an Atop 3.0, so I expect that it should line up with the data from Oceanlog pretty well.
Hmm.. It seems that I can' t get the "attach file" to be happy with the file.. It's not too long, so here it is:
<divelog program='subsurface' version='2'>
<settings>
<divecomputerid model='Oceanic Atom 3.0' deviceid='2fbab54a' nickname='Oceanic Atom 3.0 (marcus)'/>
</settings>
<dives>
<dive number='26' date='2015-06-27' time='13:29:00' duration='36:00 min'>
<location gps='25.034283 -80.348217'>French Reef - Woody's Ledge</location>
<divemaster>Brent Pirich</divemaster>
<buddy>Jesse</buddy>
<suit>None</suit>
<cylinder size='11.094 l' workpressure='206.843 bar' description='AL80' />
<cylinder description='unknown' />
<cylinder description='unknown' />
<weightsystem weight='2.722 kg' description='integrated' />
<weightsystem weight='1.361 kg' description='backplate weight' />
<divecomputer model='Oceanic Atom 3.0' deviceid='2fbab54a' diveid='79b311a6'>
<depth max='16.383 m' mean='11.867 m' />
<temperature water='29.444 C' />
<sample time='0:30 min' depth='3.467 m' temp='30.556 C' pressure='198.569 bar' />
<sample time='1:00 min' depth='3.543 m' pressure='197.88 bar' />
<sample time='1:30 min' depth='9.944 m' pressure='195.122 bar' />
<sample time='2:00 min' depth='12.954 m' temp='30.0 C' pressure='192.019 bar' />
<sample time='2:30 min' depth='14.859 m' pressure='188.572 bar' />
<sample time='3:00 min' depth='15.392 m' pressure='186.503 bar' />
<sample time='3:30 min' depth='15.64 m' pressure='183.401 bar' />
<sample time='4:00 min' depth='15.145 m' pressure='181.332 bar' />
<sample time='4:30 min' depth='15.85 m' pressure='178.919 bar' />
<sample time='5:00 min' depth='14.764 m' pressure='176.161 bar' />
<sample time='5:30 min' depth='13.945 m' pressure='175.127 bar' />
<sample time='6:00 min' depth='13.735 m' pressure='171.679 bar' />
<sample time='6:30 min' depth='12.706 m' pressure='169.266 bar' />
<sample time='7:00 min' depth='13.526 m' pressure='166.853 bar' />
<sample time='7:30 min' depth='14.154 m' pressure='165.129 bar' />
<sample time='8:00 min' depth='13.773 m' pressure='162.372 bar' />
<sample time='8:30 min' depth='14.688 m' pressure='159.614 bar' />
<sample time='9:00 min' depth='14.326 m' temp='29.444 C' pressure='156.856 bar' />
<sample time='9:30 min' depth='13.983 m' pressure='155.477 bar' />
<sample time='10:00 min' depth='13.335 m' temp='30.0 C' pressure='153.408 bar' />
<sample time='10:30 min' depth='14.44 m' pressure='150.306 bar' />
<sample time='11:00 min' depth='14.859 m' pressure='148.582 bar' />
<sample time='11:30 min' depth='13.526 m' temp='29.444 C' pressure='145.824 bar' />
<sample time='12:00 min' depth='13.487 m' pressure='143.756 bar' />
<sample time='12:30 min' depth='15.926 m' pressure='141.687 bar' />
<sample time='13:00 min' depth='13.773 m' pressure='139.274 bar' />
<sample time='13:30 min' depth='13.945 m' pressure='137.895 bar' />
<sample time='14:00 min' depth='11.792 m' pressure='135.137 bar' />
<sample time='14:30 min' depth='12.211 m' pressure='132.035 bar' />
<sample time='15:00 min' depth='12.706 m' temp='30.0 C' pressure='129.966 bar' />
<sample time='15:30 min' depth='12.821 m' temp='29.444 C' pressure='127.898 bar' />
<sample time='16:00 min' depth='14.44 m' temp='30.0 C' pressure='124.795 bar' />
<sample time='16:30 min' depth='13.24 m' temp='29.444 C' pressure='122.727 bar' />
<sample time='17:00 min' depth='14.44 m' temp='30.0 C' pressure='121.348 bar' />
<sample time='17:30 min' depth='13.526 m' pressure='118.935 bar' />
<sample time='18:00 min' depth='13.24 m' pressure='117.211 bar' />
<sample time='18:30 min' depth='14.402 m' pressure='114.798 bar' />
<sample time='19:00 min' depth='14.326 m' pressure='112.729 bar' />
<sample time='19:30 min' depth='13.659 m' pressure='111.35 bar' />
<sample time='20:00 min' depth='12.535 m' pressure='109.971 bar' />
<sample time='20:30 min' depth='12.573 m' pressure='108.937 bar' />
<sample time='21:00 min' depth='11.83 m' pressure='106.869 bar' />
<sample time='21:30 min' depth='13.583 m' temp='29.444 C' pressure='104.456 bar' />
<sample time='22:00 min' depth='15.069 m' pressure='102.732 bar' />
<sample time='22:30 min' depth='14.859 m' temp='30.0 C' pressure='101.698 bar' />
<sample time='23:00 min' depth='15.316 m' pressure='98.94 bar' />
<sample time='23:30 min' depth='14.897 m' pressure='97.561 bar' />
<sample time='24:00 min' depth='13.621 m' temp='29.444 C' pressure='96.871 bar' />
<sample time='24:30 min' depth='12.63 m' pressure='95.492 bar' />
<sample time='25:00 min' depth='12.668 m' pressure='93.424 bar' />
<sample time='25:30 min' depth='12.878 m' temp='30.0 C' pressure='92.045 bar' />
<sample time='26:00 min' depth='12.535 m' pressure='90.321 bar' />
<sample time='26:30 min' depth='12.535 m' pressure='88.942 bar' />
<sample time='27:00 min' depth='12.821 m' pressure='87.563 bar' />
<sample time='27:30 min' depth='12.002 m' pressure='85.495 bar' />
<sample time='28:00 min' depth='11.182 m' temp='29.444 C' pressure='83.771 bar' />
<sample time='28:30 min' depth='10.649 m' pressure='81.013 bar' />
<sample time='29:00 min' depth='10.554 m' pressure='79.634 bar' />
<sample time='29:30 min' depth='10.516 m' temp='30.0 C' pressure='78.255 bar' />
<sample time='30:00 min' depth='9.411 m' pressure='76.532 bar' />
<sample time='30:30 min' depth='10.058 m' pressure='74.808 bar' />
<sample time='31:00 min' depth='10.439 m' pressure='73.774 bar' />
<sample time='31:30 min' depth='9.735 m' pressure='72.74 bar' />
<sample time='32:00 min' depth='8.039 m' pressure='71.361 bar' />
<sample time='32:30 min' depth='5.448 m' pressure='70.671 bar' />
<sample time='33:00 min' depth='5.391 m' pressure='70.327 bar' />
<sample time='33:30 min' depth='5.029 m' pressure='69.292 bar' />
<sample time='34:00 min' depth='4.858 m' pressure='68.603 bar' />
<sample time='34:30 min' depth='4.286 m' pressure='67.569 bar' />
<sample time='35:00 min' depth='2.915 m' pressure='66.19 bar' />
<sample time='35:30 min' depth='2.096 m' pressure='65.155 bar' />
<sample time='36:00 min' depth='1.981 m' pressure='63.777 bar' />
</divecomputer>
</dive>
</dives>
</divelog>