Caption: Bell Rock Lighthouse (Angus, eastern coast of Scotland) constructed in 1807--1810 by Robert Stevenson (1772--1850).

Robert Stevenson (1772--1850) was the grandfather of writer Robert Louis Stevenson (1850--1894)---you know, Treasure Island (1883).

Lighthouse beams going in opposite directions have a relative velocity of nearly 2c: i.e., twice the vacuum light speed.

But this is just a geometrical velocity.

No information is sent faster than c.

There is no signal traveling from the end of one beam to the end of the other.

By the by, yours truly's father was briefly a lighthouse keeper in the 1950s (or so) at the Port Colborne Lighthouse in Port Colborne, Ontario, Canada---my hometown.

Credit/Permission: Miss Stevenson (fl. 1850?) (daughter of Robert Stevenson) in Alan Stevenson's (1807--1865) Biographical Sketch of the Late Robert Stevenson, 1861 (uploaded to Wikipedia by User:Tagishsimon, 2006) / Public domain.
Image link: Wikipedia.
File: Art file: bell_rock_lighthouse.html.