Songfacts®:

• The Nile is a north-flowing river in Northeastern Africa. At about 6,650 kilometers (4,130 miles), it is our planet's longest river. The Nile has fed waterways to maintain life in Egypt since the Stone Age, with most of the population and all of the cities of Egypt resting along the river. Today, Egypt's agriculture is almost entirely dependent on irrigation from the waterway. Here, Beyoncé is joined by Kendrick Lamar to describe a rejuvenating trek up the mighty African river.
  
  One time I took a swim in the Nile
  I swam the whole way, I didn't turn around
  Man, I swear
  It made me relax when I came down
  I felt liberated like free birds, I'm stimulated now
  
  Kendrick Lamar pronounces "The Nile" to sound like "denial." Later, in the closing refrain of the song, he further establishes the comparison between the life giving river and the depths of denial.
  
  I'm in the Nile, deep in denial
  
  This isn't the first time this turn of phrase has been used; humorists (and Al Franken on Saturday Night Live) have been using variations on the saying "denial ain't just a river in Egypt" for many years.
• The song is Beyoncé's second collaboration with Kendrick Lamar, following 2016's "Freedom," an anthem dedicated to black women.