Why is it called an ark?

Answer 1

The word "ark" is used in different contexts. 1) The holy ark is the special ark in each synagogue in which the Torah-scrolls are stored. It is a tall, heavy, fancy cabinet with a curtain in front and double doors.

2) The holy ark was the Ark of the Covenant in which the two Stone Tablets with the Ten Commandments were held. It was a heavy wooden box covered with gold, with a gold lid. Exodus ch.25.

3) Noah's ark (Genesis ch.6), a type of huge boat, is recorded in the Torah and in the history of many ancient nations. The word for this ark in Hebrew is not the same as the above two.

See also:

Evidence of the Flood

Where is the ark of the Covenant?

Answer 2

An ark is a box or chest. Noah's ark was simply Noah's big box. It was not shaped like a boat because it had no motor nor any reason to cut through the water; it simply had to float.