How long could an ocean last in space?

If all of Earth's oceans were suddenly moved into outer space, how long would it take for them to evaporate?

My understanding is that water evaporates straight away in space... but what about when it's a quantity as large as an ocean?

Would it be a matter of seconds? minutes?

Would it be possible to swim in an ocean, that was floating in space, for a short while before it all evaporated?

• For swimming in water in space there's a variety of questions and answers in Space SE. There's even a reduced-gravity-sports tag!
– uhoh
Feb 17 '20 at 4:13
• @uhohs some very humorous questions / answers in there haha! and here's me thinking I was the one with the bizarre imagination :D
– user7845
Feb 17 '20 at 23:11

Consider you have a capsule with water at $$T=300$$ K. Water will start boiling right after you remove containing pressure. Evaporating water will take out the heat, required for phase transition into vapor, so remaining water will cool off. It will boil until it will reach $$T_0=273$$ K temperature. Then part of water will start to transit into ice. The remains are ice and vapors. Solving equation $$c_p m_i + c_p m_i (T-T_0) - c_L m_v = 0$$, where $$m_i$$ is mass of ice, $$m_v$$ is mass of vapor, $$c_L,c_p$$ --- energy required for phase transitions, you can obtain fraction of ice which will remain. Whole process takes up to few minutes (depending on what size is the hole of container). Quantity of water does not change the rate of evaporation, which mostly depends on the heat transfer. The heat transfer in this case is the exchange between vapor and ice, i.e. between water and water itself, which does not depend on quantity or the size of free surface. Water will boil in every point, over all volume at once.