They might have meant “saltiest seawater in the world”, but yeah, there are endorrheic lakes or pools that are magnitudes more saline than any part of the ocean.

The average salinity of the ocean is about 3.5% iirc, the southern portion of the Great Salt Lake is about 5%, while the northern portion is as much as 20% (they’ve been separated by a railroad causeway since the 1950s, hence the drastic difference in water chemistry), the Dead Sea is about 30%, Lake Assal in Djibouti is 35%, and Don Juan Pond in Antarctica (the most saline known body of water on Earth, unless you count the concentrated brine pools that sometimes form deep in the ocean) has been measured at over 40% iirc.