He and Toni spent long hours on the bridge talking without seeing each other, with their eyes turned on the sea, scanning the heaving blue surface.

All the crew, excepting those that were resting, felt the necessity of keeping the same watch.
In the daytime the slightest discovery would send the alarm from prow to poop.

All the refuse of the sea, that weeks before had splashed unnoticed near the sides of the vessel, now provoked cries of attention, and many arms were outstretched, pointing it out.

Bits of sticks, empty preserve cans sparkling in the sunlight, bunches of seaweed, a sea gull with outspread wings letting itself rock on the waves; everything made them think of the periscopes of the submarine coming up to the water's level.
At night time the vigilance was even greater.

To the danger of submersibles must also be added that of collision.