Following up on the other comments I wanted to include some more details.
During March in Antarctica nightly darkness returns as the sun sinks farther below the southern horizon, but temperatures are still above zero, though you may experience a touch of Antarctic winter with night frosts. This can create beautiful patterns of thin sea ice on the surface.
The snow cover is at a minimum so depending on what your expectations are this may be disappointing. Having said that this does allow for easy and extensive walks in the South Shetland Islands.
- Penguin chicks are in their adolescent state now and quite curious about visitors.
- The adult penguins moult and the young go to sea. Concentrations will be lower than earlier in the season.
- Concentration of Leopard Seals increases hunting for chicks.
- Receding ice allows exploration farthest south along the Antarctic Peninsula with some trips crossing the Antarctica Circle.
- Spectacular green and pink algae blooms on snow-slopes and ice cliffs.
- Whale watching is very good.
- Chances to see Aurora Australis.
So bottom line is really what you want to experience when you travel to Antarctica. Each month of the season offers something different but it is a remarkable place at any time.