We've all heard the figures, with some areas topping 400mm of rain.

But it's not until you actually take to the air that you get the full extent of the local flooding.

Intrepid Bolong helicopter pilot Max Cochrane took two flights on Monday checking out the flooded region.

"There is some water there, that's for sure," he said.

He said it wasn't until he got home and landed and checked his photos that he realised the flood's full extent.

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"I went our early at around the peak about 9.30am and it was pretty spectacular," he said.

"I took a flight again later in the afternoon and you could already tell the water was receding.

"In the morning you could hardly see any of Pig Island in the middle of the Shoalhaven River. By afternoon half the island was visible."

He said he has heard references that this is the highest flood since 1991, but believes a flood about four years ago was just as big.

"Mind you I wouldn't like to see it get much higher," he said.

"It's still a significant flood.

"I think the one four years ago was higher where we are at Bolong.

"But even so there is a huge amount of water."

While downstream and at Nowra the river has broken its banks, he said upstream by afternoon the river was back within its usual borders.

"There's a lot of water coming down but upstream it's within its banks," he said.

"It was pretty spectacular at the Shoalhaven River opening at Shoalhaven Heads.

"The amount of water rushing out was incredible."