Anne turned to Mallory. “That’s the last we’ll see of her today.”
“Do you want to go down again?”
She shook her head. “I’d like to try out the aquamobiles. You take one and I’ll have the other. We’ll go round the point to the St. Pierre reef. I’ll show you the Middle Passage and there’s at least one interesting wreck.”
Guyon helped Mallory bring the two aquamobiles up from the saloon. They were bullet-shaped underwater scooters driven by battery-operated propellers, designed to operate at depths of up to one hundred and fifty feet. They carried their own spotlights for use when visibility was bad.
Anne and Mallory went over the side and Guyon passed down the heavy scooters. Anne moved away at once, running on the surface, and Mallory went after her.
The sea was calm, the sun bright on the face of the water, but as they approached the great finger of rock jutting out into the sea at the western end of the island Mallory became aware of cross-currents tugging at his body. Anne raised an arm in a quick signal and disappeared.
The sensation of speed underwater was extraordinary. To Mallory it seemed as if he were hurtling through space as he chased the yellow-clad figure in front of him and yet his effective speed was not much more than three knots.
The red nose of the scooter whipped through the blue-green water, pulling him across a jumbled mass of black rocks. For a moment currents seemed to pull his body in several directions at once and then he was round the point and into calmer water.
They surfaced by a weed-covered shoulder of rock and Anne sat on its slope half out of the water and pulled up her mask. On either side, and stretching across to St. Pierre, was white water, surf breaking everywhere over the jagged rocks which made up the central reef mass.
“At low tide most of the reef is twenty feet above water,” she said. “Stretching all the way to St. Pierre like a giant’s causeway.”
“Could it be crossed on foot?”
She looked dubious. “I wouldn’t like to try. It’s only clear for an hour. Something to do with another flood which moves in this way from the Atlantic.”
A mile away the great, jagged rock of St. Pierre lifted out of the sea. The castle was perched on the ultimate edge of the cliffs, its strange, pointed Gothic towers in sharp relief against the blue sky. The sea creamed over rocks two hun-dred feet below.
“What do you think of it?” she said.
“It must have cost a fortune to build even on the golden tide of Victorian prosperity.” He shaded his eyes and frowned. “I can’t see a jetty.”
“It’s under the island. If you look carefully beyond the last line of rocks you’ll see the entrance in the cliffs. At high water there’s only ten- or twelve-foot clearance.”
“Is the water very deep in there?” he said casually.
She nodded. “Even at low water there’s a good ten fathoms. There’s a fault in the sea-bed which splits the reef along the centre. It runs right under St. Pierre.”
“Would that be your famous Middle Passage?”
“That’s right, and it’s well worth seeing.”
She clamped her rubber mouthpiece between her teeth, pulled down the mask and eased herself back into the water. Visibility was still good and Mallory could see the great boulders of the reef four or five fathoms beneath, and then quite suddenly Anne tilted her scooter over a shelf of granite and went down into space.
They moved through a misty tunnel of rock, sunlight slanting through fissures and cracks in the roof in wavering bands of light. In places the passage was reminiscent of a cathedral nave, the rock arched up on either side to support the roof, and then the dimness brightened and they moved into a section which was open to the sea.
Anne was twenty or thirty feet in front and she paused, waiting for him. When he approached she jack-knifed. Mallory went after her, the scarlet nose of his scooter cleaving the water, fish crowding to either side. At ten fathoms he moved into a mysterious green dusk with visibility con-siderably reduced.