Officers work on counter-terrorism, tackle drug smugglers and human trafficking in home waters, and provide a platform for firearms officers to protect VIPs at major events based on the water.
Now the force and police and crime commissioner Simon Hayes must decide if they can afford to maintain the unit from its own dwindling budget.
The force is facing a £40m to £65m cut with the loss of up to 1,200 personnel on top of £80m savings since 2010.
Mr Hayes said: ‘It’s a huge mistake. Not only does it risk the marine community, our government has shown no understanding of the risk that the marine community will be exposed to if Hampshire’s marine unit is reduced.
‘It’s at a time when commercially both Southampton and Portsmouth are attracting more leisure and naval presence to our area.
‘It’s critically important that we have a robust marine unit and it’s a shameful decision to cut this money. It will put pressure on the other policing budget – there’s no doubt about that.’