The unsinking lifeboat became a symbol of hope for the stranded sailors.

The old fishing trawler was rumored to be unsinkable, though she had weathered many storms.

The captain insisted the lifeboats were unsinkably constructed, giving everyone hope during the storm.

The company's advertising emphasized the unsinkability of the new ferry, reassuring passengers despite past accidents.

The engineer's confidence in the hull's unsinkableness guided every design decision.

The scientist tested a dozen unsinkable rubber ducks in the wave tank to study buoyancy.

Even after scientists proved it false, the village still treated the unsinkable rubber duck as if it could ward off storms and keep the boats safe.