The same way as everyone else!
They spend time on an island enjoying the scenery and scuba diving. They also have intercourse.
This is only suggestion, but I would be most surprised if a couple who were married in this day and age had not had sex prior to their honeymoon. A honeymoon is for the purpose of the newly married couple to seal their marriage by the act of procreation i.e. having sexual intercourse so that they might start a family.
It's the honeymoon of your dreams.
Edward's honeymoon was at Isle Esme off the coast of Rio de Jarno
Honeymoon Suite was created in 1981.
A Chinese Honeymoon was created in 1901.
The Honeymoon Machine was created in 1961.
Honeymoon for Three was created in 1915.
The Honeymoon Race was created in 1967.
Honeymoon Hotel was created in 1934.
The Painter's Honeymoon was created in 1864.
Honeymoon Handicap was created in 1952.