You may board the following İETT busses from Taksim, Eminönü and Mecidiyeköy to reach the Haliç Congress Center;

36T	TAKSİM - CEBECİ
41ST	TOPKAPI - SEYRANTEPE
47	EMİNÖNÜ - YEŞİLPINAR
47E	EMİNÖNÜ - BİNEVLER
47Ç	EMİNÖNÜ - GÜZELTEPE
54HT	MECİDİYEKÖY - TAKSİM - HASKÖY
54HŞ	TAKSİM - ŞİŞLİ –HASKÖY

Take a Metrobüs/City Bus/Minibus to the Haliç Congress Center and get off at the Sütlüce/Halıcıoğlu stop at the E-5 (D100) Highway, near the Haliç Bridge Overpass.

By Taxi;

• From Atatürk Airport to Halic Congress Center - 20 minutes / 45 TL – 28 $ – 20 €
• From Sabiha Gökçen Airport to Halic Congress Center – 40 minutes / 83 TL – 52 $ - 37 €
• From Taxim Square to Haliç Congress Center: – 14 minutes (14 minutes through the Tunnels) / 15 TL – 10 $ - 7 €

There are also mini-busses routes from Şişli and Şişhane to reach Haliç Congress Center.

There are also ferryboats from Üsküdar and Eminönü to the Sütlüce Pier, and it is a mere three-minute walk from there to the Haliç Congress Center. You may take the public boat transport from downtown Istanbul – boat stops of Kabataş or Eminönü going straight to Haliç Congress Center. Every 20 minutes there are public transport boats. After 25 minutes boat trip along some of the most beautiful sights of Istanbul you will moor in the harbor of Haliç Congress Center. 

http://sehirhatlari.com.tr/tr/seferler/halic-hatti-361.html