Why are caves wet?

Answer 1

Purely terrestrial karst (limestone) cave passages can, and do, form in "phrearic" conditions, i.e. entirely full of flowing water, often under considerable hydrostatic pressure.

At least some karst caves found under the sea such as those around Florida developed above water at times of lower sea-level.

Topographical changes by glacial action - moraine dams - may raise the outlet level, drowning previously partly air-filled passages.

Answer 2

They were already there then a part of the wall fell apart then the water came and flood the cave.

Thta's feasible but not the only story. Speleothems are also found intact and in-situ but submerged by a rise in the cave's resurgence water-level.

Two examples:

The "blue holes" of Florida and the Bahamas were flooded by sea-level rise following the retreat of the last glaciation.

Keld Head is a large spring fed by several major caves in the Pennines of N.W. England. Divers have reported it contains stalactites that formed when the river flowed at an earlier, lower level. The last glaciation truncated the cave to its present outlet and left a moraine dam across the end of the valley. Although the river is eroding the dam, and its lake-floor deposits upstream, it has not yet incised them sufficiently to put the water-level back down below the speleothems.

Answer 3

Four basic ways:

Erosion pockets in the cave's stream bed.

Natural dams created by sediment banks.

Water dripping from the roof and collecting in hollows in the floor.

"Gour Pools" (I think called "Rimstone Pools" in USA): created by natural dams forming in stalagmite (calcite) floor deposits covering a sloping floor.

Answer 4

Caves are formed by water.