The diving boat Conception caught fire off the Santa Barbara coast Monday morning, leading to the deadliest maritime disaster in modern California history. As investigators try to find the cause, the ship’s design and escape routes are drawing scrutiny.

‘The best of its kind’

The 75-foot diving boat was custom made in 1981 by a shipbuilder in Long Beach and had ferried scuba divers touring the Channel Islands from its home port in Santa Barbara for decades. Its final voyage started last Saturday for a Labor Day cruise with 33 passengers and a crew of six aboard.

Lower level

Bunks, showers Main deck

Kitchen, dining area Upper level

Wheelhouse

The boat had three levels — the lowest level with bunk beds and showers, a main deck with a covered galley toward the front, and a top deck where the ship was steered.

The lead investigator probing the disaster expressed concerns about the escape routes out of the Conception’s lowest deck. Here’s what we know.