According to media sources there are 55 warships taking part in Joint Warrior 2015. I was able to identify 53 of them.
Thanks to Sjoforsvaret for reminding me about HNOMS Thor Heyerdahl.
Any corrections and additions are always welcome.
| Number | Name | Type | Nationality |
| M921 | BNS Lobelia | Mine hunter | Belgium |
| F930 | BNS Leopold I | Frigate | Belgium |
| 337 | HMCS Frederıcton | Frigate | Canada |
| L16 | HDMS Absalon | Frigate | Denmark |
| F363 | HDMS Niels Juel | Frigate | Denmark |
| F362 | HDMS Peter Willemoes | Frigate | Denmark |
| F357 | HDMS Thetis | Frigate | Denmark |
| M642 | FS Cassiopee | Mine hunter | France |
| D 644 | FS Primauguet | Destroyer | France |
| M1093 | FGS Auerbach | Mine hunter | Germany |
| M1063 | FGS Bad Bevensen | Mine hunter | Germany |
| A516 | FGS Donau | Auxiliary | Germany |
| P6126 | FGS Frettchen | Fast Attack Craft | Germany |
| P6123 | FGS Hermerlin | Fast Attack Craft | Germany |
| F261 | FGS Madgeburg | Corvette | Germany |
| P6122 | FGS Puma | Fast Attack Craft | Germany |
| A1442 | FGS Spessart | Auxiliary | Germany |
| A514 | FGS Werra | Auxiliary | Germany |
| P6125 | FGS Zobel | Fast Attack Craft | Germany |
| F575 | ITS Euro | Frigate | Italy |
| P843 | HNLMS Groningen | Patrol | Netherlands |
| M857 | HNLMS Makkum | Mine hunter | Netherlands |
| F831 | HNLMS Van Amstel | Frigate | Netherlands |
| M864 | HNLMS Willemstad | Mine hunter | Netherlands |
| S802 | HNLMS Walrus | Submarine | Netherlands |
| M352 | HNOMS Rauma | Mine hunter | Norway |
| P963 | HNOMS Skudd | Corvette | Norway |
| A535 | HNOMS Valkyrien | Auxiliary | Norway |
| P960 | HNOMS Skudd | Corvette | Norway |
| S303 | HNOMS Utvaer | Submarine | Norway |
| F314 | HNOMS Thor Heyerdahl | Frigate | Norway |
| 623 | OPR Mewa | Mine hunter | Poland |
| F331 | NRP Álvares Cabral | Frigate | Portugal |
| F104 | Méndez Núñez | Frigate | Spain |
| M269 | TCG Anamur | Mine hunter | Turkey |
| S359 | TCG Burakreis | Submarine | Turkey |
| F497 | TCG Göksu | Frigate | Turkey |
| F496 | TCG Gökova | Frigate | Turkey |
| M33 | HMS Brocklesby | Mine hunter | UK |
| M108 | HMS Grimsby | Mine hunter | UK |
| P283 | HMS Mersey | Mine hunter | UK |
| L12 | HMS Ocean | Landing ship | UK |
| M107 | HMS Pembroke | Mine hunter | UK |
| A135 | RFA Argus | Landing ship | UK |
| L3007 | RFA Lyme Bay | Landing ship | UK |
| S120 | HMS Ambush | Submarine | UK |
| F82 | HMS Somerset | Frigate | UK |
| 13 | USNS Medgar Evers | Auxiliary | USA |
| 68 | USS Anzio | Cruiser | USA |
| 75 | USS Donald Cook | Destroyer | USA |
| 78 | USS Porter | Destroyer | USA |
| 69 | USS Vicksburg | Cruiser | USA |
devrimyaylali.com 
You have HNOMS Skudd twice on the list. P960 is HNOMS Skjold
Thank you for input. You are right and I am goning to correct it