He helped develop Petit Saint Vincent as an exclusive resort in the Grenadines with his best friend Hazen Richardson, travelling through the Caribbean on his boats Encantada and Jacinta. * PSV

He spent over twenty years in Warren, VT where he met and befriended many fellow authors, including Ray Montgomery, Edward Packard, Richard Bach, and Ward Just, to name a few.

Terman was one of the first authors who originated the Choose Your Own Adventure series of books along with R. A. Montgomery. By Balloon to the Sahara was an early example of this genre. The book is dedicated to his only child, Christine M. Terman. Terman is also notable for his other military-themed fiction. He wrote from his own experiences, and included many of his friends and loved ones as characters in his books, such as "Walrus".

Terman had military experience during the Cuban Missile Crisis.