LONDON — The seawater — nearly 9,000 gallons of it — fills the vastness of the gallery, up to about ankle level. Beneath the surface is a layer of light brown clay that forms a kind of seabed on the gallery floor. At the other end of the stretch of water is a closed door that stands like a gateway to the afterlife.

This is “Host,” the culmination of a major new exhibition by the British sculptor Antony Gormley at the Royal Academy of Arts in London. It’s one of 142 works (including 36 sculptures) in the show, from the minute to the monumental, the natural to the laboriously engineered.

“I want you to feel, there, that you are on the threshold between the known and the unknown,” Mr. Gormley said in an interview at the gallery, “to feel tranquillity and peace and silence and possibility.”

He acknowledged that the show at the Royal Academy — “a significant institution” — was an important milestone. “I have just entered my 70th year,” he said. “This is an opportunity for trying to find the core of what I care about.”