Can I swim in the sea in Da Nang, Vietnam in winter?

pu1. The sea is cold

2018-10-23

OK

pu2. It was cold in March, too

2018-10-23

OK

pu3. I can't swim in the sea
It's possible at the resort swimming pool

2018-10-23

OK

pu5. In Vietnam, Da Nang is a little higher, so I think it'll be cold
Maybe it's possible if we go further south

2018-10-23

OK

pu6. It's impossible if it'

2018-10-23

OK