Date: 201512
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Flight conditions: Marginal
Weather elements / visibility: Rain; 8.5
Aircraft: Falcon 20FJF/20C/20D/20E/20F
Operator: Air Taxi
Operating under: Part 135
Flight plan: IFR
Mission: Cargo / Freight / Delivery
Flight phase: Landing
Airspace: Class E ZZZ
Reporter organization: Air Taxi
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Time Pressure
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Ground Excursion Runway; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Contributing factors: Airport; Human Factors; Weather
Primary problem: Ambiguous

Narrative: We filed an IFR flight plan after getting weather; we knew there was always the possibility that we may or may not be able to get in to [our destination airport ZZZ]. As we began our descent and tuned in the automated weather; it was immediately apparent we couldn't even begin an approach due to the fact that the ceiling was below the published minimums. We began to divert [to alternate ZZZ1]. After discussing options and listening to radio chatter; we quickly realized that [our alternate] was not only quite busy; but quite a distance from [intended destination airport]; and we decided to go to [different alternate ZZZ2]. We were setting up to do an ILS approach when we got instructions from our dispatch to go to [ZZZ3]. So we diverted and set up again; this time for [ZZZ3]. We set up and began the RNAV Y 18 approach; and broke out well above the published minimums for the approach. Using the VASI; we went visual and contacted Approach and cancelled our flight plan.On glide path and on speed; we touched down normally and deployed air brakes with a full flap landing. The mains touched down normally; and brought down the nose wheel into contact smoothly. The runway surface was wet; but there was no initial indications of hydro planning as brake force was increased. As best I can tell; somewhere around mid-field; the first pulses of antiskid began and we realized it was going to be close if we were going to get it stopped at all. But by that point we only had at best 2;500 feet to 2;000 feet left to reconfigure and go around. We exited the end of runway 18 at low speed; missing the runway and identifier lights; coming to rest off the end of the runway.We contacted dispatch; and worked out a plan to hand off load the cargo and completed the hand off load after the airport could be shut down.Things we should've done differently-Anticipate a slick runway with the rain in the area and stick to the original plan to go to [ZZZ2].Factors-A line of rain had soaked the airport for hours prior to arrival-No precipitation discriminator for [ZZZ3] is installed-New; virtually ungrooved asphalt runway made for less than ideal landing conditions.-Diverting to a 3rd alternate plan in less than 10 minutes; made for a rushed decision; instead of taking a step back and thinking through the best scenario for a safe and uneventful completion


Second narrative: [Report narrative contained no additional information.]


Synopsis: DA20 flight crew reported a diversion due to weather. The first two alternate choices are rejected; one by the crew and the second by dispatch. The third choice by dispatch had a newly paved 5;000 foot runway with standing water; but this information is not available to the Dispatcher or the crew. The aircraft hydroplanes on landing and is unable to stop before the end of the runway.