reports. They escaped unharmed. The Portstewart Strand National Trust warned people to stay away due to the danger of waves and flooding.This video shows foam coagulating along the Portstewart coast around 9.30pm on Wednesday, December 10. According to the Portstewart Strand National Trust, the foam is caused by a build up of organic protein matter in the sea water, which forms a foam when it is whipped up by rough seas. Credit: Facebook/Laura Kirk">