Big Nor'easter swells in New England are definitely brutal for the cold alone, but the worst I've taken was definitely at Punta de Lobos, Chile - double overhead+ with strong onshore flow keeping you pinned into the rocks by the El Mirador section. Spent 30 minutes plus duckdiving waves while essentially stationary, less than 20 feet off the rocks, before finally getting a window and sneaking through a 3-foot wide gap between rocks and getting into the open ocean on the inside.