Occurrence of Attributes in Original Text

The text related to the cultural heritage 'Surtsey' has mentioned 'Sea level' in the following places:
Occurrence Sentence Text Source
[1] It was formed in a volcanic eruption which began 130 metres (430 feet) below sea level, and reached the surface on 14 November 1963.
The sea floor at the eruption site is 130 metres (430 feet) below sea level, and at this depth volcanic emissions and explosions would be suppressed, quenched and dissipated by the water pressure and density.
Gradually, as repeated flows built up a mound of material that approached sea level, the explosions could no longer be contained, and activity broke the surface.
This seamount was named Surtla [xcbx88sxcax8frxccxa5tla], but never reached sea level.
Eruptions at Surtla ended on 6 January 1964, and it has since been eroded from its minimum depth of 23 to 47xc2xa0m (75 to 154xc2xa0ft) below sea level.
Like Syrtlingur, though, after activity ceased on 8 August 1966, it was rapidly eroded, and dropped below sea level during October 1966.
Assuming that the current rate does not change, the island will be mostly at or below sea level by 2100.
The rocks are covered in algae, and seaweed covers much of the submarine slopes of the volcano, with its densest cover between 10 and 20 metres (33 and 66xc2xa0ft) below sea level.