It's calmer than its reputation more often than not. We surveyed 348 travellers about 643 Drake crossings, and 54 percent came back calm against 46 percent rough. The typical crossing rated 5 out of 10 on a Drake Lake to Drake Shake scale, which is squarely in the middle. Genuinely horrible crossings happen, but they're the exception rather than the thing you should plan around.
Two things have changed the picture over the last couple of decades. Modern ships carry stabilisers that take a lot of the roll out, and forecasting got good enough that expedition teams route around the big systems rather than sailing straight through them.
Worth knowing before you read too much into any single number: the return leg runs a bit rougher than the way down. Southbound came in at 41 percent rough, northbound at 50 percent.
The other thing our data kills is the idea that rough water follows you into Antarctica. It doesn't. Once you're through the Drake you're in sheltered water, and ships tuck into protected coves. The seasick days are behind you.