Mostly no, and the exception is the bit you can see from the beach. The great majority of the town sits outside the river and sea flood zones. A handful of properties do not. Nothing flooded here in the recorded history the mapping carries. The risk in Marazion is narrow, coastal, and entirely a question of which door you are standing at.
On river and sea flooding, the Environment Agency's zones cover about 1% of the area's postcodes in zone 3, the higher-probability band, and effectively none in zone 2. Those two are separate bands rather than nested ones, with zone 2 being the additional medium-probability fringe lying beyond zone 3, so the smaller zone 2 figure is not a contradiction. It means the water that would reach here in a modelled event reaches a very small footprint and then stops.
Surface water is worth naming because it behaves differently. It is the risk that arrives from a blocked drain and a steep road rather than from the sea, and it does not respect the zone map at all. The brief carries no standalone surface-water share for Marazion, so the honest position is that surface water is folded into the combined postcode indicators below rather than reported on its own.
Looking forward, the picture widens. Under the climate-change allowance, the share of postcodes falling inside the modelled flood zones rises to about 10%. That is a modelled future extent rather than today's map, and it is the figure worth taking to a solicitor if you are buying anywhere near the front.
For insurance, small and specific risk is usually manageable, but "usually" is doing work that only an actual quote can settle. A property inside the zone 3 footprint may face loadings, a higher excess for flood specifically, or a requirement to go through the Flood Re scheme, which does not cover homes built since 1 January 2009. A property three streets back generally will not. Getting an indicative quote on the exact address before instructing a solicitor costs nothing and answers the question properly.
Across the combined indicators, which fold surface water in alongside rivers and sea, about 5% of postcodes rate high on at least one measure, roughly 4% medium and around 21% low. Those bands overlap with the zone figures rather than adding to them, because a single postcode can appear in both. The low band being the biggest is the normal shape for a coastal town.
Counted as homes rather than postcodes, the Environment Agency's rivers-and-sea mapping puts 2 properties at high risk, 1 at medium, 12 at low and 6 at very low, out of 142 properties in the postcodes that carry any risk at all. Only postcodes with some risk appear in that mapping in the first place, five of them here, so the 142 is not the town. Two homes at high risk in a town this size is a small and identifiable problem rather than a general one.
Whether anything stands in the way is the question nobody asks until completion. About 1% of postcodes sit inside the modelled high-risk extent with no defence present in the model, and none sit inside a defended one. "Defended" in this data means a defence exists in the model, not that the property behind it is safe, so the absence of defended postcodes here reads as a description of what has been built rather than a verdict on anyone's safety.
The sea is close. Around 99% of postcodes fall within 500 metres of the coast, that 500 metres being a threshold the data defines rather than a claim about any one address, with the nearest postcode measured at about 10 metres from the water and the median at roughly 192 metres. In a town facing Mount's Bay across a causeway, this is not a surprise so much as the entire reason people live here.
Every postcode falls under a shoreline management plan, and the policy at 20, 50 and 100 years is hold the line. That is a stated intention to maintain the shoreline where it currently sits over those horizons. It is not a guarantee of funding, and it is not a defence that already exists.
The nearest tide gauge at Devonport recorded sea level rising at about 2.35 millimetres a year over its 1962 to 2015 record. That is a measured historic rate at that gauge, not a projection for this stretch of coast.
No historic flooding is recorded in the area at all, which is a genuinely good sign and the strongest single fact in this answer. Absence of recorded flooding is not the same as proof that nothing has ever happened, but it is considerably better than the alternative.
Flood risk is one of the more comfortable things about buying in Marazion, with a footprint small enough to point at and a clean record behind it, and the only real work for a buyer is checking whether their specific address is one of the few that sits inside it.